Compositions and Foam Compositions Containing Composite Particles, Articles, Composite Particles, and Methods

ABSTRACT

Compositions are provided including an uncrosslinked thermoplastic nitrogen-containing matrix material and composite particles distributed in the matrix material. The composite particles each include a chemical blowing agent particle encapsulated within a shell including an uncrosslinked thermoplastic material. The uncrosslinked thermoplastic material exhibits at least a certain minimum complex viscosity at a decomposition temperature of the chemical blowing agent particle. Also described are foam compositions and particles including the foam compositions, such as a sheet or multilayer construction. Composite particles are further provided. Methods of making the foam compositions are additionally described herein. Also, polishing pads, polishing systems, and methods of polishing a substrate are provided.

FIELD

The present disclosure relates to compositions and foam compositionsincluding composite particles containing chemical blowing agents,articles, and methods of forming the foam compositions.

BACKGROUND

Foams are porous materials that are composed of gas filled networks orchambers segmented by a solid matrix. The properties of foamed materialsare governed by the composition of the matrix material and themorphology of its cellular structure. Chemical blowing agents, physicalblowing agents, and expandable microspheres have all been employed toassist in forming foamed materials.

SUMMARY

Compositions, foam compositions, and articles containing compositeparticles, methods of making foam compositions, and composite particlesare provided. The composite particles include an encapsulated chemicalblowing agent particle. Use of the composite particles tends to lead toa decrease in foam cell size and a concomitant increase in foam celldensity and homogeneity, as compared to materials foamed with the samechemical blowing agent that is not encapsulated.

In a first aspect, a composition is provided. The composition includesan uncrosslinked thermoplastic nitrogen-containing matrix material and aplurality of composite particles distributed in the uncrosslinkedthermoplastic nitrogen-containing matrix material. The compositionexhibits an elastic modulus of 0.5 megaPascals (MPa) or greater. Theplurality of composite particles each includes a chemical blowing agentparticle encapsulated within a shell including an uncrosslinkedthermoplastic material. The uncrosslinked thermoplastic materialexhibits a complex viscosity of 3,700 Pascal seconds (Pa·s) or greaterat a decomposition temperature of the chemical blowing agent particle.

In a second aspect, a foam composition is provided. The foam compositionincludes a closed cell foam thermoplastic nitrogen-containing matrixmaterial and an uncrosslinked thermoplastic material distributed in theclosed cell foam thermoplastic nitrogen-containing matrix material.

In a third aspect, an article is provided. The article includes a foamcomposition attached to a substrate. The foam composition includes aclosed cell foam thermoplastic nitrogen-containing matrix material andan uncrosslinked thermoplastic material distributed in the closed cellfoam thermoplastic nitrogen-containing matrix material.

In a fourth aspect, a method of making a foam composition is provided.The method includes a) compressing a mixture; and b) heating thecompressed mixture, thereby forming the foam composition. The mixtureincludes an uncrosslinked thermoplastic nitrogen-containing matrixmaterial and a plurality of composite particles distributed in theuncrosslinked thermoplastic nitrogen-containing matrix material. Themixture exhibits an elastic modulus of 0.5 MPa or greater. The pluralityof composite particles each includes a chemical blowing agent particleencapsulated within a shell including an uncrosslinked thermoplasticmaterial. The uncrosslinked thermoplastic material exhibits a complexviscosity of 3,700 Pa·s or greater at a decomposition temperature of thechemical blowing agent particle.

In a fifth aspect, a composite particle is provided. The compositeparticle includes a chemical blowing agent particle encapsulated withina shell including an uncrosslinked thermoplastic material; and aco-encapsulated metal salt. The metal salt is of the form MX or M(X)₂,wherein M is zinc, calcium, cadmium, potassium, barium, strontium,magnesium, mercury, titanium, tin, lead, sodium, lithium, or cesium,wherein X is an organic or inorganic ligand containing a nitrate,phosphate, phosphite, sulfate, carbonate, an oxalic acid, a halide,para-toluenesulfonate, tetrafluoroborate, perchlorate, hydroxide, orcyanide moiety and the corresponding hydrates, or mixtures thereof. Theuncrosslinked thermoplastic material exhibits a complex viscosity of3,700 Pa·s or greater at a decomposition temperature of the chemicalblowing agent particle.

In a sixth aspect, a composition is provided. The composition includesan uncrosslinked thermoplastic matrix material and a plurality of thecomposite particles of the fifth aspect distributed in the uncrosslinkedthermoplastic matrix material.

In a seventh aspect, another foam composition is provided. The foamcomposition includes a closed cell foam thermoplastic matrix materialand a plurality of the composite particles of the fifth aspectdistributed in the closed cell foam thermoplastic matrix material.

In an eighth aspect, a polishing pad is provided. The polishing padincludes a foam composition of the second aspect or the seventh aspect.

In a ninth aspect, a polishing system is provided. The polishing systemincludes the polishing pad of the eighth aspect and a polishingsolution.

In a tenth aspect, a method of polishing a substrate is provided. Themethod includes providing a polishing pad of the eighth aspect having aworking surface; providing a substrate having a first surface;contacting the working surface of the polishing pad with the firstsubstrate surface; and moving the polishing pad and the substraterelative to one another while maintaining contact between the workingsurface of the polishing pad and the first substrate surface. Polishingis conducted in the presence of a polishing solution.

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples may beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list. Thus, the scope of the present disclosure should not belimited to the specific illustrative structures described herein, butrather extends at least to the structures described by the language ofthe claims, and the equivalents of those structures. Any of the elementsthat are positively recited in this specification as alternatives may beexplicitly included in the claims or excluded from the claims, in anycombination as desired. Although various theories and possiblemechanisms may have been discussed herein, in no event should suchdiscussions serve to limit the claimable subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an apparatus for making anexemplary foam composition.

FIG. 2A is a Scanning Electron Microscopy (SEM) image of the foamcomposition of Comparative Example A foamed for 5 minutes at 230° C.

FIG. 2B is an SEM image of the foam composition of Comparative Example Bfoamed for 5 minutes at 230° C.

FIG. 2C is an SEM image of the foam composition of Example 1 foamed for5 minutes at 230° C.

FIG. 2D is an SEM image of the foam composition of Comparative Example Cfoamed for 4 minutes at 230° C.

FIG. 2E is an SEM image of the foam composition of Example 2 foamed for3.9 minutes at 230° C.

FIG. 2F is an SEM image of the foam composition of Comparative Example Dfoamed for 6.5 minutes at 270° C.

FIG. 2G is an SEM image of the foam composition of Example 7 foamed for6.5 minutes at 270° C.

FIG. 2H an SEM image of the foam composition of Comparative Example Efoamed for 5 minutes at 270° C.

FIG. 2I is an SEM image of the foam composition of Example 8 foamed for6.5 minutes at 270° C.

FIG. 3A is a photographic image of the foam composition of Example 9extruded at a die temperature of 430° F.

FIG. 3B is a photographic image of the foam composition of ComparativeExample G extruded at a die temperature of 390° F.

FIG. 4A is an SEM image of the multilayer composite of Example 20,wherein the slice was taken in the transverse direction.

FIG. 4B is an SEM image of the multilayer composite of Example 20,wherein the slice was taken in the machine direction.

FIG. 5A is an SEM image of the foam composition of Comparative Example Gextruded at a die temperature of 246° C., wherein the slice was taken inthe transverse direction.

FIG. 5B is an SEM image of the foam composition of Comparative Example Gextruded at a die temperature of 246° C., wherein the slice was taken inthe machine direction.

FIG. 5C is an SEM image of the foam composition of Example 23 extrudedat a die temperature of 246° C., wherein the slice was taken in thetransverse direction.

FIG. 5D is an SEM image of the foam composition of Example 23 extrudedat a die temperature of 246° C., wherein the slice was taken in themachine direction.

FIG. 6 is a photographic image of a surface of the foam composition ofExample 23.

FIG. 7A is a light microscope image of the foam composition of Example24 extruded at a die temperature of 285° C.

FIG. 7B is a light microscope image of the foam composition of Example24 extruded at a die temperature of 302° C.

FIG. 8A is an SEM image of the foam composition of Example 23 extrudedat a die temperature of 246° C., having a smooth major surface.

FIG. 8B is an SEM image of the foam composition of Example 22 extrudedat a die temperature of 229° C., having a smooth major surface.

FIG. 8C is an SEM image of the foam composition of Comparative Example Gextruded at a die temperature of 218° C., having a rough major surface.

FIG. 9A is an SEM image of the foam composition of Example 25 foamed for8 minutes at a temperature of 150° C.

FIG. 9B is an SEM image of the foam composition of Comparative Example Hfoamed for 8 minutes at a temperature of 150° C.

FIG. 10 is an SEM image of the foam composition of Example 29 foamed for9 minutes at a temperature of 150° C.

FIG. 11 is an SEM image of the foam composition of Example 30 foamed for5 minutes at a temperature of 190° C.

FIG. 12A is an SEM image of the foam composition of Example 31 foamedfor 12 minutes at a temperature of 150° C.

FIG. 12B is an SEM image of the foam composition of Comparative ExampleI foamed for 12 minutes at a temperature of 150° C.

FIG. 13 is a graph of complex viscosity versus temperature foruncrosslinked thermoplastic materials.

DETAILED DESCRIPTION Compositions

In a first aspect, a composition is provided. The composition comprises:an uncrosslinked thermoplastic nitrogen-containing matrix material and aplurality of composite particles distributed in the uncrosslinkedthermoplastic nitrogen-containing matrix material, wherein thecomposition exhibits an elastic modulus of 0.5 megaPascals (MPa) orgreater, and wherein the plurality of composite particles eachcomprises: a chemical blowing agent particle encapsulated within a shellcomprising an uncrosslinked thermoplastic material, wherein theuncrosslinked thermoplastic material exhibits a complex viscosity of3,700 Pa·s or greater at a decomposition temperature of the chemicalblowing agent particle.

Elastic modulus of the composition can be determined experimentally,such as using dynamic mechanical analysis (DMA). The elastic modulus ofthe compositions is 0.5 MPa or greater, 0.1 MPa, 0.5 MPa, 0.75 MPa, 1.0MPa, 1.50 MPa, 2 MPa, 5 MPa, 7 MPa, 10 MPa, 12 MPa, 15 MPa, 20 MPa, 25MPa, 30 MPa, 40 MPa, 50 MPa, 75 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa,300 MPa, 350 MPa, 400 MPa, or 450 MPa or greater; and 5,000 MPa or less,4,500 MPa, 4,000 MPa, 3,500 MPa, 3,000 MPa, 2,500 MPa, 2,000 MPa, 1,500MPa, 1,000 MPa, or 500 MPa or less. At such elastic moduli, thecompositions are suitable for casting or compressing in a foamingprocess, as opposed to spray foaming.

The components of the composition are described in detail below.

Uncrosslinked Thermoplastic Matrix Materials

The uncrosslinked thermoplastic nitrogen-containing matrix materialincludes materials having at least one nitrogen atom in the backbone ofthe thermoplastic matrix material. In some embodiments, theuncrosslinked thermoplastic nitrogen-containing matrix material isselected from a polyamide, a poly(ester amide) (PEA), a polyurethane, apolyethyleneimine, a polyimide, a polyetherimide (PEI), a polyurea, apolyoxazoline, a polyiminothioether, a polyaminoamide, apolysulfonamide, a poly(amide-imide), or combinations thereof. In someembodiments, the uncrosslinked thermoplastic nitrogen-containing matrixmaterial can also be blended with uncrosslinked thermoplastic materialthat does not include a nitrogen atom in the backbone but instead atleast one nitrogen atom in a pendent group (e.g., uncrosslinkedthermoplastic pendent nitrogen-containing material), such aspolyurethane blended with poly(styrene-acrylonitrile) (SAN). In someembodiments, the uncrosslinked thermoplastic nitrogen-containing matrixmaterial can also be blended with uncrosslinked thermoplasticnon-nitrogen-containing material, like polyurethane blended with variousTPEs, such as styrene-butadiene rubber, styrene-butadiene-styrene blockcopolymer (SBS), styrene-isoprene-styrene (SIS), styrene-butadienecopolymer (ABS), butadiene copolymer (nitrile rubber, NBR), etc.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyamide. As used herein, “polyamide”refers to a polymer having multiple amido groups of formula —(CO)NH—.Suitable polyamides include both acid-terminated and amine-terminatedpolyamides. Amine-terminated polyamides are more reactive with anepoxide-functionalized crosslinker than acid-terminated polyamides. Forpolyamides that exhibit slower reactivity, a crosslink catalyst may alsobe employed to increase the rate of crosslinking the uncrosslinkedthermoplastic matrix material. Crosslinkers and crosslink catalysts aredescribed further below.

In some embodiments, the polyamides of the polyamide component mayinclude the reaction product (e.g., by condensation polymerization) of adiacid component and a diamine component.

In some embodiments, the diacid component may include any long chaindiacid (e.g., diacids that include greater than 15 carbon atoms). Thediacid component may further include a short chain diacid (e.g., diacidsthat include between 2 and 15 carbon atoms). In some embodiments, thelong chain diacid may be present in the diacid component in an amount ofbetween 51-100 mol %, 70-100 mol %, 80-100 mol %, 90-100 mol %, 51-99mol. %, or 51-95 mol. %; or at least 51 mol. %, at least 70 mol. %, orat least 90 mol. %, based on the total moles of the diacid component. Insome embodiments, the short chain diacid may not be present in thediacid component, or may be present in the diacid component in an amountof between 1-49 mol %, 1-30 mol %, 1-20 mol %, or 1-10 mol. %, based onthe total moles of the diacid component.

In some embodiments, the diacid component may include a dicarboxylicacid (e.g., in the form of a dicarboxylic dimer acid). In someembodiments, the dicarboxylic acid may include at least one alkyl oralkenyl group and may contain 3 to 30 carbon atoms and may becharacterized by having two carboxylic acid groups. The alkyl or alkenylgroup may be branched. The alkyl group may be cyclic. Usefuldicarboxylic acids may include propanedioic acid, butanedioic acid,pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioicacid, nonanedioic acid, decanedioic acid, undecanedioic acid,dodecanedioic acid, hexadecanedioic acid, (Z)-butenedioic acid,(E)-butenedioic acid, pent-2-enedioic acid, dodec-2-enedioic acid,(2Z)-2-methylbut-2-enedioic acid, (2E,4E)-hexa-2,4-dienedioic acid,sebacic acid. Aromatic dicarboxylic acids may be used, such as phthalicacid, isophthalic acid, terephthalic acid and2,6-naphthalenedicarboxylic acid. Mixtures of two or more dicarboxylicacid may be used, as mixtures of different dicarboxylic acids may aid indisrupting the structural regularity of the polyamide, therebysignificantly reducing or eliminating crystallinity in the resultingpolyamide component.

In some embodiments, the diacid component may also include adicarboxylic acid with an anionic group. Useful dicarboxylic acids withan anionic group include 5-sulfoisophthalic acid, sodium salt or itsdimethyl ester, 5-sulfoisophthalic acid, lithium salt.

In some embodiments, the dicarboxylic dimer acid may include at leastone alkyl or alkenyl group and may contain 12 to 100 carbon atoms, 16 to100 carbon atoms, or 18 to 100 carbon atoms and is characterized byhaving two carboxylic acid groups. The dimer acid may be saturated orpartially unsaturated. In some embodiments, the dimer acid may be adimer of a fatty acid. The phrase “fatty acid,” as used herein means anorganic compound composed of an alkyl or alkenyl group containing 5 to22 carbon atoms and characterized by a terminal carboxylic acid group.Useful fatty acids are disclosed in “Fatty Acids in Industry: Processes,Properties, Derivatives, Applications”, Chapter 7, pp 153-175, MarcelDekker, Inc., 1989. In some embodiments, the dimer acid may be formed bythe dimerization of unsaturated fatty acids having 18 carbon atoms suchas oleic acid or tall oil fatty acid. The dimer acids are often at leastpartially unsaturated and often contain 36 carbon atoms. The dimer acidsmay be relatively high molecular weight and made up of mixturescomprising various ratios of a variety of large or relatively highmolecular weight substituted cyclohexenecarboxylic acids, predominately36-carbon dicarboxylic dimer acid. Component structures may be acyclic,cyclic (monocyclic or bicyclic) or aromatic.

In some embodiments, the diamine component may include one or moresecondary diamines or one or more secondary/primary hybrid diamines and,optionally, one or more primary diamines.

In some embodiments, suitable secondary or secondary/primary hybridamines may have the formula: R¹—NH—R²—NH—R¹,

where R² is an:

-   -   alkylene (e.g. —CH₂CH₂CH₂—),    -   branched alkylene (—CH₂CH(Me)CH₂—),    -   cycloalkylene (e.g. -cyclohexyl-CH₂-cyclohexyl-),    -   substituted or unsubstituted arylene (e.g. -1,4-Phenylene-),    -   heteroalkylene (e.g. —CH₂CH₂—O—CH₂CH₂— or any other        “JEFFAMINE”), or    -   heterocycloalkylene (e.g. —CH₂-furan ring-CH₂—);        and each R¹, independently, is a:    -   linear or branched alkyl (e.g. -Me, -isopropyl),    -   cycloalkyl (e.g. -cyclohexyl),    -   aryl (e.g. -phenyl),    -   heteroalkyl (e.g. —CH₂CH₂—O—CH₃),    -   heteroaryl (e.g., -2-substituted-pyridyl), or    -   hydrogen atom,    -   with the proviso that both R's are not hydrogen atoms, or the IV        groups are alkylene or branched alkylene and form a heterocyclic        compound (e.g. piperazine).

Suitable secondary diamines may include, for example, piperazine,1,3-Di-4-piperidylpropane, cyclohexanamine,4,4′-methylenebis[N-(1-methylpropyl)]. In some embodiments, suitablesecondary/primary hybrid diamines (i.e., diamines having a secondaryamine and a primary amine) include, for example, aminoethyl piperazine.In some embodiments, the secondary/primary hybrid diamines may not bepresent, or may be present in an amount of less than 50 mol. %, 30 mol.%, 10 mol. %, or 5 mol. %, based on the total moles of the secondary orsecondary/primary hybrid amines. In some embodiments, the number averagemolecular weight of suitable secondary diamines or secondary/primaryhybrid diamines may be from 30 g/mol to 5000 g/mol, 30 g/mol to 500g/mol, or 50 g/mol to 100 g/mol.

In some embodiments, the diamine component may, in addition to thesecondary or secondary/primary hybrid amine, include a primary diamine,such as an aliphatic or aromatic primary amine. Suitable primary aminesinclude, for example, ethylenediamine, m-xylylenediamine,1,6-hexanediamine, 1,10-decanediamine, 1,12-dodecanediamine,2,2,4(2,4,4)-trimethyl-1,6-hexanediamine, o-toluidine, or1,3-Benzenedimethanamine. In some embodiments, the number averagemolecular weight of suitable primary diamines may be from 30 g/mol to5000 g/mol, 30 g/mol to 500 g/mol, or 50 g/mol to 100 g/mol.

In some embodiments, the secondary or secondary/primary hybrid diamines,alone or in combination, may be present in the diamine component in anamount of from 1-100 mol %, 50-100 mol %, 90-100 mol %, 1-99 mol %,50-99 mol %, 70-99 mol %, 90-99 mol %, 95-100 mol %, or 95-99 mol %, or99-100 mol %, based on the total moles of the diamine component. In someembodiments, the secondary or secondary/primary hybrid diamines, aloneor in combination, may be present in the diamine component in an amountof in an amount of at least 1 mol %, 50 mol %, 90 mol %, 95 mol %, or atleast 99 mol %, based on the total moles of the diamine component.

In some embodiments, primary amines may not be present in the diaminecomponent, or may be present in the diamine component in an amount ofbetween 1-10 mol % or 1-5 mol %, based on the total moles of the diaminecomponent. In some embodiments, the mole ratio of diamine to diacid inthe polyamide component may be between 1 and 5, 1 and 4, 1.1 and 4, or1.2 and 3.

In some embodiments, it may be beneficial to substitute a portion of thediacid or diamine components with corresponding components functionalitygreater than 2. The presence of higher functionality components canresult in the formation of a crosslinked polymer with infinite molecularweight if that component is present at sufficient concentration in thecomposition. The appropriate level of the higher functionality componentcan be determined using empirical methods or by using Equation 7,Chapter 9 of “Principles of Polymer Chemistry” by Paul Flory (1953).Useful examples of acid components with functionality greater than 2 are1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarbonyl trichloride,citric acid, ethylenediamine tetraacetic acid, Pripol 1017 (availablefrom Croda, Inc., Edison, N.J.), Pripol 1025 (available from Croda,Inc., Edison, N.J.), Pripol 1040 (available from Croda, Inc., Edison,N.J.). Useful examples of diamine components with functionality greaterthan 2 are diethylenetriamine, triethylenetetraamine,1,2,4-benzenetriamine.

The diacid component can be a diacid (—COOH) or in the form ofcarboxylic acid derivatives such as the corresponding alkyl diester(—COOR, where R=linear or branched C1-C4) or the corresponding diacidchloride (—COCO. In the case of the diacid, the reaction by-product willbe water. In the case of the alkyl diester, the by-reaction product willbe the corresponding linear or branched C1-C4 alcohol. In the acid ofthe diacid chloride, the by-product will be hydrogen chloride, whichmust be removed from the reaction to enable formation of the polyamideat high yield. Typical methods for removal of the hydrogen chlorideinclude the use of tertiary amine co-solvents such as pyridine or4-(N,N′-dimethyl)aminopyridine.

In some embodiments, the polyamide component may be formed following aconventional condensation reaction between at least one of the abovedescribed diacids and at least one of the above described diamines.Mixtures of at least two diacid types with at least one diamine,mixtures of at least two diamine types with at least one diacid type, ormixtures of at least two diacid types with at least two diamine typesmay be used. The polyamide component may be amine terminated or includeamine end-groups. Amine termination can be obtained by using theappropriate stoichiometric ratio of amine groups to acid groups, e.g.the appropriate stoichiometric ratio of diamine and diacid during thesynthesis of the polyamide. Useful ranges for the amine number are 1 mgKOH/g, to 250 mg KOH/g, preferably 2 mg KOH/g to 100 mg KOH/g, morepreferably 3 mg KOH/g to 50 mg KOH/g.

In some embodiments, the polyamide component may be formed following aconventional condensation reaction between at least one of the abovedescribed diacids and at least one of the above described diamines.Mixtures of at least two diacid types with at least one diamine,mixtures of at least two diamine types with at least one diacid type, ormixtures of at least two diacid types with at least two diamine typesmay be used. The polyamides may be acid terminated or include acidend-groups. Acid termination can be obtained by using the appropriatestoichiometric ratio of acid groups to amine groups, e.g. theappropriate stoichiometric ratio of diacid and diamine during thesynthesis of the polyamide. Useful ranges for the acid number are 1 mgKOH/g, to 250 mg KOH/g, preferably 2 mg KOH/g to 100 mg KOH/g, morepreferably 3 mg KOH/g to 50 mg KOH/g.

In some embodiments, the polyamide component may include amultifunctional polyamidoamine or a hotmelt dimer acid based polyamidesuch as those described in U.S. Pat. No. 3,377,303 (Peerman et al.).

In some embodiments, the polyamide component comprises a polypeptide ora polypeptoid. Polypeptides include a chain of amino acids linkedtogether by peptide bonds, and have the structure of—[C(═O)—[CH₂]_(m)—N(R)]_(n)—. Polypeptoids are similar, and have thestructure —[C(═O)—[C(R)]_(m)—NH]_(n)—.

Poly(ester amide)s (PEAs) are prominent polymers, which can combine thestiffness and the excellent thermal and mechanical properties ofpolyamides with the biocompatibility and biodegradability of polyesters.They have been investigated and applied as biodegradable plastics forconsumables (e.g., by Bayer, under the trade designation “BAK”). Thefirst PEAs were synthesized in 1932 by Carothers from diacids, diols anddiamines.

Polyamide-imides display a combination of properties from bothpolyamides and polyimides, such as high strength, melt processibility,exceptional high heat capability, and broad chemical resistance. Theyare prepared from isocyanates and TMA (trimellic acid-anhydride) inN-methyl-2-pyrrolidone (NMP). A prominent distributor ofpolyamide-imides is Solvay Specialty Polymers, which uses the tradedesignation “TORLON”.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyurethane, such as a polyether-basedthermoplastic polyurethane, a polyester-based thermoplasticpolyurethane, or both. A polyurethane includes one or more carbamatefunctionalities in the backbone of the material. Urethanes are preparedby the reaction of an isocyanate with an alcohol to form carbamatelinkages. Moreover, the term “polyurethane” has been used moregenerically to refer to the reaction products of polyisocyanates withpolyactive hydrogen compounds including polyfunctional alcohols, andmercaptans (e.g., a polythiourethane).

In some embodiments, in addition to the urethane functionality, thepolyurethane further comprises one or more pendent functional groupsselected from carboxyl groups and siloxane groups. The polyurethane mayfurther comprise a linking group selected from alkyl, polyalkylene,polyalkylene oxide, aryl, polycarbonate, polyester, polyamide, andcombinations thereof. As used herein, “linking group” refers to afunctional group that connects two or more urethane groups. The linkinggroup may be divalent, trivalent, or tetravalent.

Suitable commercially available polyurethanes include for instance andwithout limitation, polyurethanes from Lubrizol Corporation(Brecksville, Ohio), under the trade designations “ESTANE”, “ISOPLAST”,AND “PELLETHANE”. A few examples of such polyurethanes include apolyether-based polyurethane of the trade designation “ESTANE 58144”; apolyester-based polyurethane of the trade designation “ESTANE 58277”; apolyurethane of the trade designation “ISOPLAST 101 EPT”; and anaromatic polyether-based polyurethane of the trade designation“PELLETHANE 5862-85A”.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyethyleneimine. Polyethyleneimines arepolycationic polymers and may be linear or branched. One suitablepolyethyleneimine is commercially available from Sigma Aldrich (St.Louis, Mo.) as a branched polyethyleneimine having an average weightaverage molecular weight (Mw) of about 25,000 grams per mole, and havinga linear formula of H(NHCH₂CH₂)_(n)NH₂. Additional suitablepolethyleneimine polymers include those from BASF Corporation, (FlorhamPark, N.J.) under the trade designation “LUPASOL”, such as “FG”, “PR8515”, “P”, and “PS”.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyimide. Polyimides are polymers having animide group (i.e., two acyl groups bound to a nitrogen atom), and havehigh resistance to elevated temperatures and to chemicals. Suitablecommercially available polyimides include for instance and withoutlimitation, those available from DuPont under the trade designation of“AURUM” thermoplastic polyimide resins, such as “J-1548”, “J-2556”,“JCL3010”, “JCN3030”, “PL500M”, “JCF3030”, “JCL3030”, “JGM3030”, and“PL450C”.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyetherimide (PEI). Polyetherimides havebeen developed to overcome challenges associated with polyimides whichare not readily melt processable. Incorporating the proper etherlinkages into the polyimide molecular chain provides sufficientflexibility to allow good melt processibility yet retains aromatic imidecharacteristics of excellent mechanical and thermal properties. Imidesimpart high temperature performance. Ether groups allow melt processing.Polyetherimide was first developed in 1982 by General Electric Company(now known as SABIC) under the trade name ULTEM resin, and is availablefrom several suppliers such as: SABIC, RTP Company, Lehmann & Voss,Quadrant, PolyOne, etc.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyurea. Suitable polyureas may includepolymers of polyisocyanates and polyamines. Any suitable polyisocyanatesand polyamines may be used. Suitable polyisocyanates may includearomatic isocyanates, aliphatic isocyanates, polyisocyanates, orcombinations thereof. Suitable aromatic isocyanates may includemethylene diphenyl diisocyanate, 1,4-phenylene diisocyanate,1,3-phenylene diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, diphenylmethane-2,2′-diisocyanate,naphthalene diisocyanate, 4,4′-biphenyldiisocyanate, 1,5-naphthalenediisocyanate, 2-methyl-1,5-naphthalene diisocyanate, 2,4-toluenediisocyanate and 2,6-toluene diisocyanate and mixtures of the twoisomers, diphenylmethane-2,4′-diisocyanate,4-ethyl-m-phenylenediisocyanate, or mixtures thereof. Suitable aliphaticisocyanates may include 2,4,4-trimethylhexamethylene diisocyanate,2,2,4-trimethylhexamethylene diisocyanate, 1,4-cyclohexane diisocyanate,1,3-cyclohexyl diisocyanate, trimethylhexamethylene diisocyanate,isophorone diisocyanate (IPDI), decamethylene diisocyanate, methylenediisocyanate, methylene-bis(4-cyclohexylisocyanate) (H12MDI), dimeryldiisocyanate, trans-1,4-cyclohexane diisocyanate, hexamethylenediisocyanate, or mixtures thereof. Other suitable isocyanates mayinclude polyisocyanates, including those based on any of the above.Suitable polyamines may include “JEFFAMINE” polyetheramines fromHuntsman Corporation (The Woodlands, Tex.), or mixtures thereof. Inaddition, chain extenders may be included, which are typically monomericor low molecular weight difunctional compounds. Suitable amino chainextenders may include 1,4 diaminobutane, ethylenediamine, 1,2diaminopropane, 1,3 diaminopropane, 1,2 diaminocyclohexane, isophoronediamine, secondary cycloaliphatic diamines, diethyltoluenediamine, ormixtures thereof.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyoxazoline. Polyoxazolines are preparedby the cationic ring opening polymerization of oxazolines or oxazines.One suitable polyoxazoline is poly-2-ethyl-2-oxalozine, which iscommercially available from Sigma Aldrich in a variety of number averagemolecular weights. Another way to polymerize oxazolines and oxazines isvia spontaneous zwitterionic copolymerization (SZP) with electrophilicmonomers such as acrylic acid, acrylamide, acrylates, malonates, orethylenesulfonamide. SZP leads to alternating N-acylated polyamines,N-acylated poly(amino ethers), N-acylated poly(amino ethers), N-acylatedpoly(amino sulphonamides), poly(ester imino thioethers), and N-acylatedpoly(amino amido esters). These polymers are detailed in de Jongh, et.al. Prog. Polym. Sci. 2018, 87, 228.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyaminoamide. Polyaminoamides are cationicpolymers that may be prepared by step growth polymerization. Suitablecommercially available polyaminoamides include those available fromEvonik Industries (Allentown, Pa.) under the trade designation“ANQUAMINE”, such as “360”, “401”, “419”, “456”, and “701”.

In some embodiments, the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polysulfonamide. Polysulfonamides includesulfone groups and amide groups along the backbone. Polysulfonamide pulpis sold by DuPont and is generated from the polycondensation ofdi-meta-aminodiphenylsulfone with para-phenylene diformyl chloride.Polysulfonamide pulp is also sold under the trade name TANLON byShanghai Tanlon Fiber Co. (Shanghai, China) and is generated by thepolycondensation of para-phenylene diformyl chloride withdi-meta-aminodiphenylsulfone and di-para-aminodiphenylsulfone.

In certain embodiments, the uncrosslinked thermoplasticnitrogen-containing matrix material exhibits a (e.g., Vicat) softeningpoint of 40° C. or greater, 50° C., 60° C., 70° C., 80° C., 90° C., 100°C., 110° C., 120° C., 130° C., 140° C., or 150° C. or greater; and 220°C. or less, 210° C., 200° C., 190° C., 180° C., 170° C., or 160° C. orless. The softening point is for materials that have no definite meltingpoint, such as plastics. It is taken as the temperature at which thespecimen is penetrated to a depth of 1 millimeter by a flat-ended needlewith a 1 mm² circular or square cross-section at a load of 10 Newtons(N) or 50 N. A standard test method to determine Vicat softening pointincludes ASTM D 1525.

Additional Uncrosslinked Thermoplastic Materials

As noted above, in some embodiments, the uncrosslinked thermoplasticnitrogen-containing matrix material is blended with an uncrosslinkedthermoplastic non-nitrogen-containing material and/or an uncrosslinkedthermoplastic pendent nitrogen-containing material. Moreover, in someembodiments, a composite particle according to the fifth aspect may beused with an uncrosslinked thermoplastic non-nitrogen-containing matrixmaterial and/or an uncrosslinked thermoplastic pendentnitrogen-containing matrix material to make a foam composition. Thesematerials may be selected from a polyorganosiloxane, a styrenic blockcopolymer, a polystyrene, a polyolefin, a polyolefin copolymer,polyvinyl chloride (PVC), ethylene vinyl acetate, polyacrylate,polymethacrylate, an acrylate copolymer, an acrylic block copolymer, ora polylactic acid (PLA). When PLA is employed, the composition furthercomprises: a polymer having a T_(g) of 25 degrees Celsius or greater; acrosslinking agent; and a crosslink catalyst. The polymer having a T_(g)of 25 degrees Celsius or greater is often polyvinyl acetate. In someembodiments, the crosslink catalyst comprises an alkyl or alkenylammonium, phosphonium, or imidazolium salt. The composition usually alsocomprises a plasticizer. One or more additional components can beincluded, such as a crystallization nucleating agent, an antiblockadditive, a cell stabilizer, a surfactant, or any combination thereof.

Suitable polyorganosiloxanes are described, for instance, in co-ownedU.S. Pat. No. 7,501,184 (Leir et al.) and U.S. Pat. No. 8,765,881 (Hayset al.), incorporated herein by reference in their entireties. Polyvinylchloride (PVC) is a polymer made up of a majority (e.g., at least 50%)vinyl chloride, and has been used as a matrix for foam products foryears. A suitable PVC includes a PVC compound (e.g., suitable forextrusion processing) available under the trade designation GE FE1456CPFfrom Mexichem Specialty Compounds (Leominster, Mass.).

Suitable ethylene vinyl acetates (EVAs—copolymers of ethylene with vinylacetate) include, for example, resins from DuPont (Wilmington, Del.)available under the trade designation ELVAX. ELVAX resins are copolymersof ethylene and vinyl acetate. Typical grades range in vinyl acetatecontent from 9 to 40 weight percent and in melt index from 0.3 to 500dg/min. (per ASTM D1238). Suitable ELVAX resins include grades 770, 760,750, 670, 660, 650, 565, 560, 550, 470, 460, 450, 360, 350, 310, 265,260, 250, 240, 220, 210, 205, 150, 140 and 40. Suitable EVAs alsoinclude high vinyl acetate ethylene copolymers from LyondellBasell(Houston, Tex.) available under the trade designation ULTRATHENE.ULTRATHENE materials are copolymers of ethylene and vinyl acetate.Typical grades range in vinyl acetate content from 7 to 29 weightpercent. Suitable ULTRATHENE grades include UE 630, 632, 634, 635, 637,646-04, 648, 652, 655, 656, 657, 662, 685-009, 688, 672, and 757-026.Suitable EVAs also include EVA copolymers from Celanese EVA (Dallas,Tex.) available under the trade designation ATEVA. Typical grades rangein vinyl acetate content from 7 to 23 weight percent. Suitable ATEVAgrades include 1030, 1081, 1070, 1211, 1221, 1231, 1240A, 1609, 1615,1641, 1645, 1711, 1807, 1815, 1821, 1825A, 1841, 1941C, 2306E, 2911M,and 3211.

As used herein, polyacrylates refer to polymeric materials generallyprepared by polymerizing acrylate monomers, and polymethacrylates referto polymeric materials generally prepared by polymerizing methacrylatemonomers. Acrylate and methacrylate monomers are referred tocollectively herein as “(meth)acrylate” monomers. Polymers prepared fromone or more of acrylate monomers, will be referred to collectively as“polyacrylates”, while polymers prepared from one or more ofmethacrylate monomers, will be referred to collectively as“polymethacrylates”. The polymers can be homopolymers or copolymers,optionally in combination with other, non-acrylate, e.g.,vinyl-unsaturated, monomers. The copolymers of polyacrylates areacrylate copolymers, useful as uncrosslinked thermoplastic matrixmaterial. Example suitable non-acrylate functional groups in acrylatecopolymers include for instance, ethylene, acrylamides, acrylonitriles,methacrylonitriles, vinyl esters, vinyl ethers, vinyl pyrrolidinone,vinyl caprolactam, vinyl aromatic, dioxepines. Hence, the polyacrylateor polymethacrylate is polymerized prior to being combined with monomerhaving functional groups that copolymerize with the polyacrylate orpolymethacrylate component. Specific examples of polyacrylate andpolymethacrylate polymers include those prepared from free-radicallypolymerizable (meth)acrylate monomers or oligomers, such as described inU.S. Pat. No. 5,252,694 (Willett et al.) at col. 5, lines 35-68.

As used herein, “block copolymers” refer to elastomeric components inwhich chemically different blocks or sequences are covalently bonded toeach other. Block copolymers include at least two different polymericblocks that are referred to as the A block and the B block. The A blockand the B block may have different chemical compositions and differentglass transition temperatures. Block copolymers of the presentdisclosure can be divided into four main classes: di-block ((A-B)structure), tri-block ((A-B-A) structure), multi-block(-(A-B)_(n)-structure), and star block copolymers ((A-B)_(n)-structure).Di-block, tri-block, and multi-block structures may also be classifiedas linear block copolymers. Star block copolymers fall into a generalclass of block copolymer structures having a branched structure. Starblock copolymers are also referred to as radial or palmtree copolymers,as they have a central point from which branches extend. Blockcopolymers herein are to be distinguished from comb-type polymerstructure and other branched copolymers. These other branched structuresdo not have a central point from which branches extend.

Suitable acrylic block copolymers comprise at least one acrylic monomer.Exemplary acrylic block copolymer may comprise monomer units including:alkyl ester methacrylates such as, e.g., methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butylmethacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecylmethacrylate, stearyl methacrylate, isobornyl methacrylate, benzylmethacrylate, or phenyl methacrylate; alkyl ester acrylate such as,e.g., n-hexyl acrylate, cyclo hexyl acrylate, 2-ethyl hexyl acrylate,n-octyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate,n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butylacrylate, or 2-octylacrylate; (meth)acrylate esters such as, e.g., thosehaving the following ester groups: methoxy ethyl(meth)acrylate, ethoxyethyl(meth)acrylate, diethyl amino ethyl meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-amino ethyl(meth)acrylate, glycidyl(meth)acrylate, tetrahydro furfuryl(meth)acrylate;isobornyl(meth)acrylate, and combinations thereof. The acrylic blockcopolymer may comprise additional monomer units, for example, vinylgroup monomers having carboxyl groups such as, e.g., (meth)acrylic acid,crotonic acid, maleic acid, maleic acid anhydride, fumaric acid, or(meth)acryl amide; aromatic vinyl group monomers such as, e.g., styrene,α-methyl styrene, or p-methyl styrene; conjugated diene group monomerssuch as, e.g., butadiene or isoprene; olefin group monomers such as,e.g., ethylene, or propylene; or lactone group monomers such as, e.g.,ε-caprolactone or valero lactone; and combinations thereof. Onerepresentative acrylic block copolymer is available from Kuraray (Tokyo,Japan), as the trade designation KURARITY LA2330.

Suitable styrenic block copolymers include for instance,styrene-isoprene-styrene copolymers, acrylonitrile-butadiene-styrenecopolymers, styrene-butadiene-styrene copolymers, styrene-diene blockcopolymers, and styrene-ethylene-butylene-styrene copolymers. Examplestyrenic block copolymers may include linear, radial, star and taperedstyrene-isoprene block copolymers such as KRATON D1107P, available fromKraton Polymers (Houston, Tex.), and EUROPRENE SOL TE 9110, availablefrom EniChem Elastomers Americas, Inc. (Houston, Tex.), linearstyrene-(ethylene/butylene) block copolymers such as KRATON G1657available from Kraton Polymers, linear styrene-(ethylene/propylene)block copolymers such as KRATON G1657X available from Kraton Polymers,styrene-isoprene-styrene block copolymers such as KRATON D1119Pavailable from Kraton Polymers, acrylonitrile-butadiene-styrenecopolymers such as LUSTRAN ABS 348 available from INEOS (London, UK),linear, radial, and star styrene-butadiene block copolymers such asKRATON D1118X, available from Kraton Polymers, and EUROPRENE SOL TE 6205available from EniChem Elastomers Americas, Inc., orstyrene-ethylene-butylene-styrene copolymers, such as, for example thepolymer KRATON G4609H, commercially available from Kraton Polymers.

Styrene acrylonitrile resin is a copolymer plastic consisting of styreneand acrylonitrile. It is also known as SAN, and is widely used in placeof polystyrene owing to its greater thermal resistance. The relativecomposition is typically between 70 to 80% by weight styrene and 20 to30% acrylonitrile.

ABS is a terpolymer made by polymerizing styrene and acrylonitrile inthe presence of polybutadiene. The proportions can vary from 15 to 35%acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. The result is along chain of polybutadiene criss-crossed with shorter chains ofpoly(styrene-co-acrylonitrile). The nitrile groups from neighboringchains, being polar, attract each other and bind the chains together,making ABS stronger than pure polystyrene. The styrene gives the plastica shiny, impervious surface. The polybutadiene, a rubbery substance,provides toughness even at low temperatures. For the majority ofapplications, ABS can be used between −20 and 80° C. (−4 and 176° F.) asits mechanical properties vary with temperature.

Nitrile rubber, also known as NBR, Buna-N, and acrylonitrile butadienerubber, is a synthetic rubber copolymer of acrylonitrile (ACN) andbutadiene. Trade designation include “PERBUNAN”, “NIPOL”, “KRYNAC”, and“EUROPRENE”. This material is a family of unsaturated copolymers of2-propenenitrile and various butadiene monomers (1,2-butadiene and1,3-butadiene).

Suitable polyolefin polymers include for instance and withoutlimitation, semicrystalline polymer resins such as polyolefins andpolyolefin copolymers (e.g., based upon monomers having between 2 and 8carbon atoms such as low density polyethylene, high densitypolyethylene, polypropylene, ethylene-propylene copolymers, etc.),polyesters and co-polyesters, fluorinated homopolymers and copolymers,polyalkylene oxides (e.g., polyethylene oxide and polypropylene oxide),polyvinyl alcohol, ionomers (e.g., ethylene-methacrylic acid copolymersneutralized with base), and cellulose acetate and combinations thereof.

Suitable polylactic acid (“PLA”) polymers are described, for instance,in co-owned U.S. Application Publication No. 2017/0313912 (Zhou et al.),incorporated herein by reference. When PLA is included, the PLA cancomprise an amorphous PLA polymer alone, a semicrystalline PLA polymeralone, or both in combination. Suitable examples of semicrystalline PLAinclude NATUREWORKS INGEO 4042D and 4032D. These polymers have beendescribed in the literature as having molecular weight Mw of about200,000 g/mole; Mn of about 100,000 g/mole; and a polydispersity ofabout 2.0. Another suitable semicrystalline PLA is available as“SYNTERRA PDLA”. A suitable amorphous PLA includes NATUREWORKS INGEO4060D grade. This polymer has been described in the literature to have amolecular weight Mw of about 180,000 g/mole.

When the uncrosslinked thermoplastic matrix comprises PLA, thecomposition further comprises a second polymer, such as polyvinylacetate polymer. The second polymer can improve the compatibility of thePLA with a plasticizer such that the plasticizer concentration can beincreased without plasticizer migration. The second (e.g., polyvinylacetate) polymer has a T_(g) of at least 25° C., 30° C., 35° C. or 40°C. The T_(g) of the second (e.g., polyvinyl acetate) polymer istypically no greater than 80° C., 75° C., 70° C., 65° C., 60° C., 55°C., 50° C. or 45° C. Polyvinyl acetate polymers are commerciallyavailable from various suppliers including Wacker Chemie AG (Munich,Germany) under the trade designation VINNAPAS and from Vinavil AmericasCorporation (West Chicago, Ill.) under the trade designation VINAVIL. Asingle second (e.g., polyvinyl acetate) polymer may be utilized or acombination of two or more second (e.g., polyvinyl acetate) polymers.The total amount of second (e.g., polyvinyl acetate) polymer present inthe composition described herein is at least about 10 wt. % andtypically no greater than about 50, 45, or 40 wt. %, based on the totalweight of the foam composition. In some embodiments, the concentrationof second (e.g., polyvinyl acetate) polymer is present in an amount ofat least 15 or 20 wt. %.

Typically, the composition further comprises a plasticizer. The totalamount of plasticizer in the composition typically ranges from about 5wt. % to about 35, 40, 45 or 50 wt. %, based on the total weight of thecomposition. Various plasticizers that are capable of plasticizing PLAhave been described in the art. The plasticizers are generally a liquidat 25° C. and typically have a molecular weight ranging from about 200g/mol to 10,000 g/mol. Various combinations of plasticizers may beutilized.

The plasticizer preferably comprises one or more alkyl or aliphaticesters or ether groups. Multi-functional esters and/or ethers aretypically preferred. These include alkyl phosphate esters, dialkyletherdiesters, tricarboxylic esters, epoxidized oils and esters, polyesters,polyglycol diesters, alkyl alkylether diesters, aliphatic diesters,alkylether monoesters, citrate esters, dicarboxylic esters, vegetableoils and their derivatives, and esters of glycerine. Such plasticizersgenerally lack aromatic groups and halogen atoms and are anticipated tobe biodegradable. Such plasticizers commonly further comprise linear orbranched alkyl terminal group groups having a carbon chain length of C₂to C₁₀.

Representative citrate-based plasticizers include for example, triethylcitrate, acetyl triethyl citrate, tributyl citrate, acetyl tributylcitrate, trihexyl citrate, acetyl trihexyl citrate, trioctyl citrate,acetyl trioctyl citrate, butyryl trihexyl citrate, acetyltris-3-methylbutyl citrate, acetyl tris-2-methylbutyl citrate, acetyltris-2-ethylhexyl citrate, and acetyl tris-2-octyl citrate.

In another embodiment, the plasticizer comprises a polyethylene glycolbackbone and ester alkyl terminal groups. The molecular weight of thepolyethylene glycol segment is typically at least 100, 150 or 200 g/moleand no greater than 1,000 g/mole. In some embodiments, the polyethyleneglycol segment has a molecular weight no greater than 900, 800, 700, or600 g/mole. Examples include polyethylene glycol (400) di-ethylhexonate18midazoli from Hallstar, Chicago, Ill. under the trade designation“TEGMER 809” (“TegMeR™ 809”) and tetraethylene glycol di-ethylhexonateavailable from Hallstar, Chicago, Ill. under the trade designation“TEGMER 804” (“TegMeR™ 804”).

In another embodiment, the plasticizer is a substituted or unsubstitutedaliphatic polyester, such as described in U.S. Pat. No. 8,158,731(Stefanisin et al.); incorporated herein by reference. In someembodiments, the aliphatic polyester plasticizer comprises repeatingunits derivable from succinic acid, glutaric acid, adipic acid, and/orsebacic acid. In some embodiments, the polyesters of the polymer blendsdisclosed herein comprise repeating units derivable from 1,3-propanedioland/or 1,2-propanediol. In some embodiments, the polyesters of thepolymer blends disclosed herein comprise one or two terminator unitsderivable from 1-octanol, 1-decanol, and/or mixtures thereof. In someembodiments, the polyesters of the polymer blends disclosed hereincomprise repeating units derivable from succinic acid, glutaric acid,adipic acid, and/or sebacic acid; repeating units derivable from1,3-propanediol and/or 1,2-propanediol; and one or two terminator unitsderivable from 1-octanol, 1-decanol, and/or mixtures thereof. Onerepresentative aliphatic polyester plasticizer is available fromHallstar, Chicago, Ill., as the trade designation HALLGREEN R-8010. Insome embodiments, the plasticizer compound typically has little or nohydroxyl groups. In some embodiments, the wt. % percent of hydroxylgroups relative to the total weight of the plasticizer compound is nogreater than 10, 9, 6, 7, 6, 5, 4, 3, 2, 1 wt. %. In some embodiments,the plasticizer compound contains no hydroxyl groups. Thus, in thisembodiment, the plasticizer is not glycerol or water.

The properties of foam compositions can be further controlled throughthe addition of one or more of crosslinking agents, crosslink catalysts,antiblock additives, surfactants, and/or cell stabilizers, which assistin forming a foam composition using a low melt viscosity material as theuncrosslinked thermoplastic matrix material in a composition. In someembodiments, the crosslink catalyst comprises an alkyl or alkenylammonium, phosphonium, or imidazolium salt. Once modified, at least someof these foam systems can be extruded or molded into parts with desiredproperties.

Suitable crosslinking agents (e.g., crosslinkers) are often lowmolecular weight polymers that contain multiple acid, amine or alcoholreactive functionality, such as reactive polymers selected from amultifunctional epoxide, a glycidyl epoxy resin, an isocyanate, abismaleimide, a multifunctional acrylate, a cycloaliphatic epoxy resin,a polyfunctional aziridine, a polycarbodiimide, or combinations thereof.When used, the crosslinking agent is present in an amount of at least0.005 wt. %, 0.01 wt. %, 0.025 wt. %, 0.05 wt. %, 0.1 wt. %, 0.25 wt. %,0.5 wt. %, 1.0 wt. %, or at least 2.0 wt. %, based on the total weightof the composition; and up to 10 wt. %, 5.0 wt. %, 4.5 wt. %, 4.0 wt. %,3.5 wt. %, 3.0 wt. %, 2.5 wt. %, 1.0 wt. %, or up to 0.5 wt. %, based onthe total weight of the composition. Useful crosslinking agents (e.g.,crosslinkers) include for instance and without limitation the “JONCRYL”chain extenders available from BASF Corporation (Sturtevant, Wis.), forexample under the trade designations “JONCRYL 4370-F”, “JONCRYL 4368-C”,“JONCRYL ADR 4300”, “JONCRYL ADR 4370”, “JONCRYL ADR 4380”, “JONCRYL ADR4385”, and “JONCRYL ADR 4368”; and an oxazoline functionalized polymeravailable from Nippon Shokubai (Osaka, Japan) under the tradedesignation “EPOCROS RPS-1005”. Useful polyfunctional aziridines includefor instance and without limitation the aziridines available under thetrade designation “PZ-28”, “PZ-33” “PZP-1000”, “PZE-1000”, or “PZBI-25”from PolyAziridin LLC (Medford, N.J.)

In certain embodiments, the foam composition further comprises acrosslink catalyst to increase the rate of crosslinking as compared tothe rate of crosslinking in the absence of the crosslink catalyst. Insome embodiments, the crosslink catalyst is present in an amount of atleast 0.005 wt. %, 0.01 wt. %, 0.025 wt. %, 0.05 wt. %, 0.1 wt. %, 0.25wt. %, 0.5 wt. %, or at least 0.75 wt. %, based on the total weight ofthe composition; and up to 4 wt. %, 2.50 wt. %, 2.25 wt. %, 2.0 wt. %,1.75 wt. %, 1.5 wt. %, 1.25 wt. %, or up to 1.0 wt. %, based on thetotal weight of the composition.

In certain embodiments, the crosslink catalyst comprises an alkyl oralkenyl ammonium, phosphonium, or imidizolium salt. Useful crosslinkcatalysts include for instance and without limitation crosslinkcatalysts of formula (I), (II), (III), or (IV):

Q(R³)₄X  (I);

QR³(R⁴)₃X  (II);

QR⁵(R⁴)₃X  (II);

Q(R⁵)₃R³X  (IV);

wherein Q is nitrogen or phosphorous; R³ is a C₁-C₂₀ alkyl or alkenylgroup; R⁴ is a C₁-C₈ alkyl or alkenyl group; R⁵ is a phenyl group, abenzyl group, or a polycyclic aromatic hydrocarbon group; and X is ananion selected from bromide, iodide, chloride, acetate, sulfate,carbonate, phosphate, tosylate, or hexafluorophosphase. In certainembodiments, Q is N; R³ is a C₁-C₁₂ alkyl group; R⁴ is a C₁-C₈ alkylgroup; R⁵ is a phenyl group; and X is an anion selected from bromide,iodide, or chloride. Some suitable crosslink catalysts include, forexample, dodecyltrimethylammonium bromide, tetrabutylammonium bromide,tetrabutylammonium iodide, tetraoctylammonium bromide,tetrabutylammonium chloride, and triphenyl monoalkyl phosphonium salts.

Composite Particles

The plurality of composite particles of the composition each comprises:a chemical blowing agent particle encapsulated within a shell comprisingan uncrosslinked thermoplastic material, wherein the uncrosslinkedthermoplastic material exhibits a complex viscosity of 3,700 Pa·s orgreater at a decomposition temperature of the chemical blowing agentparticle. The composite particles are as described in detail above withrespect to the first aspect. Typically, the composite particles arepresent in an amount of 0.1 wt. % or greater of the total composition,0.25 wt. %, 0.5 wt. %, 1 wt. %, 2 wt. %, 3 wt. %, 4 wt. %, 5 wt. %, 6wt. %, 7 wt. %, 8 wt. %, 9 wt. %, or 10 wt. % or greater; and 20 wt. %or less, 19 wt. %, 18 wt. %, 17 wt. %, 16 wt. %, 15 wt. %, 14 wt. %, 13wt. %, 12 wt. %, or 11 wt. % or less of the total composition. Statedanother way, in some embodiments the composite particles are present inan amount of 0.5 wt. % to 20 wt. %, inclusive; 0.5 to 15 wt. %, 0.5 wt.% to 10 wt. %, 1 to 8 wt. %, or 10 wt. % to 17 wt. %, inclusive, of thetotal composition. In embodiments in which a composition is foamed in anoven, the composite particles are often present in an amount of 5 wt. %to 15 wt. %, such as 10 wt. %. In embodiments in which a composition isfoamed in an extruder, the composite particles are often present in anamount of 0.1 wt. % to 10 wt. %, such as 5 wt. %.

The composite particle may be useful in forming a polymeric foam. Foamsare porous materials that are composed of gas filled networks orchambers segmented by a solid matrix. The properties of foamed materialsare governed by the composition of the matrix material and themorphology of its cellular structure. For certain applications, theproperties of foamed materials improve as the cells in the matrixdecrease in size and increase in density and homogeneity. Therefore,optimization of the foam structure can be desirable when designing foamarticles.

Control over the morphology of a foam's cell structure is often governedby the foaming method to which the matrix material is subjected.Historically, foaming has been achieved using either physical blowingagents (PBAs), which take advantage of the change in volume that occursduring first order phase transitions such as evaporation and sublimationor when a gas experiences a decrease in pressure; or chemical blowingagents (CBAs), which are molecules that decompose to gaseous specieswhen heated. One's choice in PBAs and CBAs has remained relativelyunchanged since the 1950's; however, some disadvantages are associatedwith each. For instance, hydrocarbon PBAs are considered volatileorganic chemicals (VOCs) while chlorofluorocarbons andhydrochlorofluorocarbons are ozone depletants; these designations arebecoming increasingly undesirable for many applications. Further, whengases such as nitrogen or carbon dioxide are used as PBAs, specialtyhigh pressure rated reaction vessels and extruders are needed to createthe pressure drop necessary to foam the matrix resin. On the other hand,CBAs often face compatibility issues and/or undesirable side reactivitywith the matrix materials. Therefore, new blowing agent innovationswould be desirable.

An advance in blowing agent technology has been the expandablemicrosphere (EMS), sold by Nouryon and Chase Corporation. Thesematerials are composed of gas or liquid hydrocarbon PBAs inside apolymer shell. When heated past the glass transition temperature (T_(g))of the shell, the shell becomes malleable and expands due to theinternal pressure of the heated PBA inside. The thickness of the shelland the quantity of PBA encapsulated is tuned to enable isotropicexpansion rather than shell rupture, leading to an increase in volume.This process leads to a syntactic foam filled with polymer shells. EMSslead to foams with very uniform cell sizes. However, the use ofhydrocarbons and their residuals after use can still be an issue forapplications that have stringent low VOC requirements. Additionally, theremnant hard shells tend to act as tougheners in soft matrix resins andalso decrease tack if used in foamed adhesives, effects which can beundesirable for tape or damping applications. Finally, the hydrocarbonin the core of the microsphere can diffuse out of the particle overtime, which limits this product's shelf life. Moreover, the leftoverhard shell may scratch or cause other defects if the foam is used forpolishing application.

The materials described herein aim to address at least certaindisadvantages of one or more of the classic physical and chemicalblowing agents and expandable microspheres. It has been discovered thatencapsulation of CBAs in uncrosslinked (e.g., thermoplastic) polymershells can lead to foam structures, after the CBA core decomposes andthe composite particles rupture to release the formed gas, withdecreased cell size and increased cell density and homogeneity ascompared to unencapsulated CBAs. Encapsulation of a chemical blowingagent by a polymer shell provides a composite particle, in which thecoating layer surrounds the core particle as a shell layer. Stateddifferently, such composite particles are core-shell particles.Additional benefits of these composite particles include that many CBAsdo not give off VOCs during use, the shell material can be selected tobe compatible with the foam matrix, and CBA particles will not diffusethrough the shell wall or degrade at room temperature and pressure thusenabling a long shelf life for the composite particles.

The chemical blowing agent is a solid particulate blowing agent and istypically selected from a diazocompound, a sulfonyl hydrazide, atetrazole, a nitrosocompound, an acyl sulfonyl hydrazide, hydrazones,thiatriazoles, azides, sulfonyl azides, oxalates, thiatrizene dioxides,isotaoic anhydride, or any combination thereof. Examples of suitablechemical blowing agents include for instance and without limitation,1,1-azodicarboxamide (AZO), p-toluene sulfonyl hydrazide (Hydrazine),p-toluenesulfonyl semicarbazide (PTSC), and 5H-phenyl tetrazole (5PT).AZO is one of the most common CBAs due to its high gas yield upondegradation and low cost. AZO decomposes when heated at or above 190° C.(with optimal temperatures between 190° C. and 230° C.), and gives off220 mL/g nitrogen and carbon monoxide in the process. Hydrazine isanother common CBA, and decomposes when heated at or above 150° C. (withoptimal temperatures between 165° C. and 180° C.), and gives off 120 to130 mL/g of ammonia, hydrogen, and nitrogen in the process. 5H-phenyltetrazole is also a suitable CBA, and decomposes when heated at or above215° C. (with optimal temperatures between 240° C. and 250° C.), andgives off 195 to 215 mL/g of nitrogen in the process. An additionalsuitable CBA is isatoic anhydride, which decomposes when heated at orabove 210° C. (with optimal temperatures between 230° C. and 250° C.),and gives off 115 mL/g of carbon dioxide in the process.

Optionally, one or more additional materials may be co-encapsulated withthe CBA. In some embodiments, the additional material comprises a metaloxide or metal salt, or combinations thereof. The metal oxide can bezinc oxide, calcium oxide, or a barium-cadmium complex, for example. Insome embodiments, the metal salt can be of the form MX or M(X)₂, whereinM is zinc, calcium, cadmium, potassium, barium, strontium, magnesium,mercury, titanium, tin, lead, sodium, lithium, or cesium, and wherein Xis an organic ligand or an inorganic ligand containing a nitrate,phosphate, phosphite, sulfate, carbonate, oxalic acid, halide,para-toluenesulfonate, tetrafluoroborate, perchlorate, hydroxide, orcyanide moiety and the corresponding hydrates. Examples of suitablemetal salts include for instance, zinc stearate, calcium stearate,barium-cadmium stearate, zinc 2-ethyl hexanoate, calcium 2-ethylhexanoate, barium-cadmium 2-ethyl hexanoate, zinc acetate, calciumacetate, zinc malonate, calcium malonate, zinc benzoate, calciumbenzoate, zinc salicylate, calcium salicylate, zinc nitrate, zincsulfate, zinc phosphate, zinc chloride, zinc bromide, zinc iodide, zincfluoride, zinc carbonate, zinc p-toluenesulfonate hydrate, zinctetrafluoroborate hydrate, zinc perchlorate, zinc hydroxide, zinccyanide, calcium nitrate, calcium sulfate, calcium phosphate, calciumcarbonate, barium phosphate, barium nitrate, barium sulfate, cadmiumphosphate, cadmium nitrate, cadmium bromide, cadmium carbonate, cadmiumchloride, cadmium iodide, cadmium perchlorate, or cadmium sulfate.Typically, the metal oxide and/or metal salt is present in the compositeparticle in an amount of 500 wt. % or less of the amount of the chemicalblowing agent, 400 wt. %, 300 wt. %, 200 wt. %, 100 wt. %, or 50 wt. %or less of the amount of the chemical blowing agent. In selectembodiments, a metal oxide or metal salt is co-encapsulated in thecomposite particle when the chemical blowing agent is1,1-azodicarboxamide or p-toluene sulfonyl hydrazide. The metal salt mayalso be present in the shell of the composite particle. It has beendiscovered that the metal oxide or metal salt can alter thedecomposition temperature of the CBA.

In a fifth aspect, a composite particle is provided. The compositeparticle includes a chemical blowing agent particle encapsulated withina shell including an uncrosslinked thermoplastic material; and aco-encapsulated metal salt. In some embodiments, the metal salt is alsopresent in the shell. The metal salt is of the form MX or M(X)₂, whereinM is zinc, calcium, cadmium, potassium, barium, strontium, magnesium,mercury, titanium, tin, lead, sodium, lithium, or cesium, and wherein Xis an organic ligand or an inorganic ligand containing a nitrate,phosphate, phosphite, sulfate, carbonate, oxalic acid, halide,para-toluenesulfonate, tetrafluoroborate, perchlorate, hydroxide, orcyanide moiety, or the corresponding hydrates. The uncrosslinkedthermoplastic material exhibits a complex viscosity of 3,700 Pa·s orgreater at a decomposition temperature of the chemical blowing agentparticle. In some embodiments, the metal salt comprises zinc nitrate,zinc sulfate, zinc phosphate, zinc chloride, zinc carbonate, zincp-toluenesulfonate hydrate, zinc tetrafluoroborate hydrate, zincperchlorate, zinc hydroxide, zinc cyanide, calcium nitrate, calciumsulfate, calcium phosphate, calcium carbonate, cadmium nitrate, cadmiumchloride, cadmium carbonate, or combinations thereof. In selectembodiments, the metal salt comprises zinc nitrate, zinc sulfate, orzinc chloride. The use of various metal oxides and metal salts isdiscussed, for instance, in International Polymer Science andTechnology, Vol. 43, No. 5, 2016, 812-819, and in U.S. Pat. Nos.3,321,413 and 3,340,209 (both to Riley et al.) and. The uncrosslinkedthermoplastic material exhibits a complex viscosity of 3,700 Pa·s orgreater at a decomposition temperature of the chemical blowing agentparticle.

Similarly, in some embodiments, the one or more additional materialsco-encapsulated with the CBA comprises a polyhydroxyl compound, an aminecontaining compound, or a carboxylic acid containing compound. Examplesof suitable polyhydroxyl compounds include for instance, glycerol,ethylene glycol, diethylene glycol, triethylene glycol, and combinationsthereof. Examples of suitable carboxylic acid containing compoundsinclude for instance, stearic acid, 2-ethylhexanoic acid, acetic acid,palmitic acid, and combinations thereof. Examples of suitable aminecontaining compounds include primary amines, for instance,monoethanolamine, diglycolamine, urea, biurea, cyanuric acid, guanidine,or combinations thereof. In select embodiments, an amine containingcompound is co-encapsulated in the composite particle when the chemicalblowing agent is p-toluene sulfonyl hydrazide.

The composite particle further includes a shell encapsulating thechemical blowing agent. It has been discovered that the use of anuncrosslinked thermoplastic material that has at least a certain minimumcomplex viscosity at the degradation temperature of the CBA alters thefoaming process, as compared to the same CBA that is either notencapsulated or is encapsulated in an uncrosslinked thermoplasticmaterial having a complex viscosity below the minimum amount at thedegradation temperature of the CBA. Accordingly, the specific shellmaterial selected will depend on the decomposition temperature of theCBA to be used. In many embodiments, the uncrosslinked thermoplasticmaterial is selected from a starch, polyvinyl pyrollidinone (PVP), acopolymer of vinylpyrrolidone and vinyl acetate, a polypropylene-basedelastomer, a styrene-isoprene-styrene copolymer, a (C₁-C₃)alkylcellulose, a hydroxyl (C₁-C₃)alkylcellulose; carboxy methylcellulose,sodium carboxymethyl cellulose, a polyoxazoline, a silicone-basedthermoplastic polymer, an olefin-based thermoplastic polymer, a phenoxyresin, a polyamide, or combinations thereof.

Water soluble starches are typically prepared by partial acid hydrolysisof starch. Examples of water soluble starches include those, forexample, that are commercially available under the trade designationLYCOAT from Roquette (Lestrem, France). Examples of water solublecelluloses include, but are not limited to, alkyl cellulose (e.g.,methyl cellulose, ethyl cellulose, ethyl methyl cellulose),hydroxylalkyl cellulose (e.g., hydroxymethyl cellulose, hydroxyethylcellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose,hydroxyethyl methyl cellulose, and hydroxyethyl ethyl cellulose), andcarboxylalkyl cellulose (e.g., carboxymethyl cellulose).

Examples of suitable uncrosslinked thermoplastic materials include forinstance and without limitation, hydroxylated starch, carboxylatedstarch, methyl cellulose, propyl cellulose, ethyl cellulose,hypromellose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose,hydroxyethyl cellulose, or combinations thereof. In certain embodiments,the uncrosslinked thermoplastic material is selected from hydroxypropylstarch, PVP, a polyamide, a styrenic copolymer, or a combinationthereof, preferably hydroxypropyl starch or PVP.

The weight average molecular weight of the uncrosslinked thermoplasticmaterial is often at least 1,000 Daltons, at least 2,000 Daltons, atleast 5,000 Daltons, or at least 10,000 Daltons. The weight averagemolecular weight can be up to 500,000 Daltons or higher. For example,the weight average molecular weight can be up to 300,000 Daltons, up to200,000 Daltons, up to 100,000 Daltons, up to 50,000 Daltons, up to20,000 Daltons. Some such uncrosslinked thermoplastic polymers can beobtained, for example, from Polysciences, Inc. (Warrington, Pa., USA).

The uncrosslinked thermoplastic material can have a higher complexviscosity than 3,700 Pa·s, for instance exhibiting a complex viscosityof 4,000 Pa·s or greater, 4,500 Pa·s or greater, 5,000 Pa·s or greater,5,500 Pa·s or greater, or 6,000 Pa·s or greater at a decompositiontemperature of the chemical blowing agent particle. Unexpectedly,although the uncrosslinked thermoplastic materials may have glasstransition temperatures below the decomposition temperature of the CBA,the shell can decrease diffusion of the gaseous CBA, affecting the foamformation. Without wishing to be bound by theory, it is believed thatthe viscous uncrosslinked thermoplastic material assists in preventingcell ripening, by minimizing the amount of gas that diffusespreferentially into a previously nucleated cell. When enough pressure isbuilt up inside the particle, the shell ruptures and a new cell isnucleated. After shell rupture and cell nucleation, the remnantuncrosslinked shell material remains dispersed in the foam matrix. Thisis based on the observed decreased cell size and increased cell densityand homogeneity upon foaming with composite particles according to atleast certain embodiments of the present disclosure, as compared to thecell size, density, and homogeneity upon foaming with unencapsulatedCBAs. Additionally, in some cases, when a cross-section of the foam orpre-foam resin is imaged (e.g. by scanning electron microscopy (SEM)),unactivated particles, particles that were in the process rupturing asthe foam was cooling, and/or remnant shell material from fully rupturedparticles, can be seen dispersed through the article. When foams areimaged this gives the interfacial surface between the foam matrix andthe closed foam cells a textured or bumpy look; as opposed to a smoothlook when unencapsulated CBAs are used. For instance, FIG. 10 is an SEMimage of the foam composition of Example 29 foamed for 9 minutes at atemperature of 150° C., and 10010 indicates just two of a plurality ofbumps on the interfacial surface between the foam matrix and the closedfoam cells.

Any suitable method can be used to deposit a coating of uncrosslinkedthermoplastic material (i.e., shell) around the chemical blowing agent(e.g., core particle). Typically, an aqueous coating composition (e.g.,coating solution or coating dispersion) is mixed with the CBA particles.Such mixture (i.e., a slurry) is then subjected to conditions effectiveto form dried composite particles as described herein.

In many techniques, the slurry can be formed into particles (e.g., byatomization), and then the particles can be dried (e.g., in a spraychamber). A suitable method for forming composite particles of thepresent disclosure is via spray drying. For instance, a slurry ofchemical blowing agent solid particles and uncrosslinked thermoplasticmaterial can be prepared, followed by spray drying using commerciallyavailable spray drying systems. Preparation of several (e.g.,representative) composite particles using spray drying techniques aredescribed in the Examples below.

For many embodiments of the composite particles, the coating layersurrounds the core particle as a shell layer. Stated differently, suchcomposite particles are core-shell particles. Prior to release of thechemical blowing agent, the composite particles have a core-shellstructure with the core particles fully containing the chemical blowingagent. In some embodiments, the shell layer (coating layer) surrounds asingle core particle (plus optional co-encapsulant(s), if present). Inother embodiments, however, the shell surrounds multiple core particles(i.e., an agglomerate of core particles). That is, the particle containsmultiple core particles within a common shell layer (coating layer). Thecore particles are not tacky. This increases the likelihood thatmultiple core particles will not adhere together before or duringapplication of the coating layer. That is, the lack of tackiness of thecore particles increases the likelihood that the coating layer will bepositioned around a single core particle rather than around multiplecore particles.

The coating layer is typically formed by mixing an aqueous coatingcomposition (e.g., coating solution or coating dispersion) with the coreparticle. The coating composition can have any desired percent solidsthat allow good mixing with the core particles. In many embodiments, themaximum percent solids often correspond to the coating composition(e.g., solution or dispersion) having the highest viscosity that can bepumped. High solids can be desirable because less water needs to beremoved during the process of forming the coating layer. If the percentsolids value is too high, however, it is more likely that the coatinglayer will surround multiple core particles. In many embodiments, dilutecoating compositions are used to increase the likelihood of formingparticles containing a single core particle.

The coating composition often contains at least 5 wt. %, 10 wt. %, 15wt. %, 20 wt. %, 33 wt. %, or at least 50 wt. % solids. The weightpercent solids corresponds to the weight percent thermoplastic materialand chemical blowing agent and any co-encapsulant in the coatingcomposition. The weight percent solids can be up to 70 wt. % or evenhigher, 60 wt. %, 50 wt. %, 40 wt. %, or up to 30 wt. %.

Spray drying (spray coating and drying) or similar processes such asfluidized bed coating and drying that can result in the formation of acoating layer with relatively uniform thickness around the coreparticles is often considered to be preferable. If conditions areselected appropriately, these processes can be used to provide particleshaving a single rather than multiple core particles. That is, thecomposite particles have a core-shell arrangement with a coating layeraround a single core particle.

With spray drying, the core particles are mixed with the coatingcomposition (e.g., coating solution or coating dispersion) to form aslurry. This slurry is then pumped to a drying chamber that contains anatomizer (to form droplets) and a drying gas. Some common types ofatomizers include a rotary wheel (centrifugal) atomizer, asingle-fluid/pressure nozzle (hydraulic) atomizer, a two-fluid nozzle(pneumatic) atomizer, and an ultrasonic atomizer. The product, which isthe dried composite particles, can be collected by various means such asby gravity or by using a cyclone, filter and bag, electrostaticseparation, or the like.

Although a variety of suitable atomization processes can be used,two-fluid nozzle atomizers are often used. With these atomizers, aprimary fluid (e.g., the slurry) is pumped through a small orifice and asecond fluid, which is typically air or nitrogen but could be anysuitable gas, is supplied near the small orifice to further atomize theprimary fluid. Increasing the ratio of the secondary fluid to theprimary fluid usually decreases the slurry droplet size and increasesthe likelihood of having a single core particle within the coatinglayer. The two-fluid system may have either internal mixing (the secondfluid is introduced into the primary fluid before exiting the finalorifice) or external mixing (the second fluid is introduced after theprimary fluid exits the final orifice). Multiple differentconfigurations can be used for introducing the second fluid relative tothe primary fluid. For example, the configuration can be a round spray(concentric ring of the second fluid surrounding the primary fluidorifice), conical/hollow spray, angle/flat spray, swirl spray, or thelike. Atomizers with these different configurations are available fromvarious suppliers such as Spraying Systems Co. (Wheaton, Ill.).

Numerous options can be used for the flow of the bulk drying gas intoand out of the drying chamber. To maintain sufficient thermal energy andto provide a drying gas with sufficient drying capacity (e.g., low dewpoint), the drying gas is usually continuously cycled through the dryingchamber. The main classes of flow patterns of the drying gas relative tothe atomized droplets (input material) are co-current flow,counter-current flow, and mixed flow. Co-current flow involves the inputmaterial travelling in the same direction as the bulk drying gas; thisis often embodied as input material travelling downward immediatelyafter atomization (e.g., being sprayed downward) along with thedownward-travelling bulk drying gas. Co-current is usually good fortemperature-sensitive systems because the hot drying gas is cooled bythe drying droplets, so the solid materials never experience thetemperature of the hot incoming drying gas. Counter-current flowinvolves the input material travelling in the opposite direction to thebulk drying gas; this is often embodied as input material travellingdownward immediately after atomization (e.g., being sprayed downward)while the bulk drying gas is travelling upward. This flow is often usedfor the most efficient drying. Mixed flow is a combination of co- andcounter-current flow, where the input material is travelling in the samedirection as the bulk drying gas in some regions, but in the oppositedirection in other regions. Most often this flow pattern is seen whenthe input material is being atomized in an upward direction, where theinput material initially travels upward from the energy imparted on itby atomization, but is subsequently pulled downward by gravity. Becausethe input material travels in two directions, the bulk drying gas willtravel with the input material in some places and against the inputmaterial in others, regardless of whether the bulk drying gas istraveling downward or upward. Mixed flow can be advantageous because ofthe higher residence times in the drying chamber it provides to thedrying solids.

The drying temperature is usually selected based on the composition ofthe core particles and the aqueous coating composition. In manyembodiments, the bulk drying gas at the outlet of the drying chamber hasa temperature near the boiling point of the dispersion medium (i.e.,water) used in the slurry (in the coating composition) to ensure thatadequate drying occurs. This does result, however, in the dried solidsreaching a temperature that is near the boiling point of the water. Inmost instances, this can be beneficial because it minimizes residualliquids, which can lead to improved flowability, and reduction ofunnecessary mass. For some particles, however, it may be undesirable touse such a high drying temperature. This can be the situation, forexample, where any component of the particles has a decompositiontemperature near the boiling point of the water contained in the slurry.In particular, care must be taken to prevent or minimize release of thechemical blowing agent from the particle. In such a situation, thedrying temperature is typically reduced below that where any undesirablealteration of the chemical blowing agent particle can occur. Drying canbe accomplished at lower temperatures, for example, by increasing theresidence time in the drying chamber, increasing the flow rate of thedrying gas, decreasing the evaporative load, or modifying the variousflow patterns.

Multiple coating layers can be positioned around the core particle.Often, multiple layers are added to provide a thicker coating layer orto alter the release characteristics of the chemical blowing agent fromthe composite particle. If multiple coating layers are used, they areusually selected to be compatible with each other. In many embodiments,the same uncrosslinked thermoplastic material is used to form themultiple coating layers.

Typically, the composite particle comprises a diameter of 1 micrometeror greater, 2 micrometers, 4 micrometers, 6 micrometers, 8 micrometers,10 micrometers, 14 micrometers, 17 micrometers, or 20 micrometers orgreater; and 60 micrometers or less, 55 micrometers, 50 micrometers, 45micrometers, 40 micrometers, 37 micrometers, 33 micrometers, 30micrometers, 27 micrometers, or 23 micrometers or less. Stated anotherway, the composite particle can comprise a diameter of 1 to 60micrometers, inclusive. An (e.g., average) diameter of the compositeparticles can be determined using scanning electron microscopy (SEM).

In certain embodiments, the chemical blowing agent is present in acomposite particle in an amount of at least 1 wt. %, 5 wt. %, 10 wt. %,20 wt. %, 30 wt. %, 40 wt. %, 50 wt. %, or at least 60 wt. %, based ontotal weight of the composite particle. In certain embodiments, thechemical blowing agent is present in a composite particle in an amountof up to 80 wt. %, 75 wt. %, 70 wt. %, or up to 65 wt. %, based on thetotal weight of the composite particle.

In certain embodiments, the shell is present in a composite particle inan amount of at least 20 wt. %, 30 wt. %, 40 wt. %, 50 wt. %, or atleast 60 wt. %, based on the total weight of the composite particle. Incertain embodiments, the shell is present in a composite particle in anamount of up to 99 wt. %, 90 wt. %, 80 wt. %, or up to 70 wt. %, basedon the total weight of the composite particle.

Additives

In certain embodiments, the composition further comprises a blowingagent comprising a plurality of expandable microspheres. The blowingagent is present in an amount ranging from 0.1 to 10 weight percent,inclusive, based on the total weight of the composition. An “expandablemicrosphere” refers to a microsphere that includes a polymer shell and acore material in the form of a gas, liquid, or combination thereof,which expands upon heating. Expansion of the core material, in turn,causes the shell to expand, at least at the heating temperature. Anexpandable microsphere is one where the shell can be initially expandedor further expanded without breaking. Some microspheres may have polymershells that only allow the core material to expand at or near theheating temperature. Hence, during the formation of the foamcomposition, at least some of the expandable microspheres will expandand form cells in the foam. Suitable expandable microspheres include forinstance and without limitation, those available from Pierce Stevens(Buffalo, N.Y.) under the designations “F30D”, “F80SD”, and “F100D”; andfrom Akzo-Nobel (Sundsvall, Sweden) under the designations “Expancel551”, “Expancel 461”, “Expancel 091”, and “Expancel 930”. Each of thesemicrospheres features an acrylonitrile-containing shell. Optionally, oneor more unencapsulated chemical blowing agents are also included in thecomposition. As described above, suitable chemical blowing agentsinclude solid particulate blowing agents such as an azo compound, adiazocompound, a sulfonyl hydrazide, a tetrazole, a nitrosocompound, anacyl sulfonyl hydrazide, hydrazones, thiatriazoles, azides, sulfonylazides, oxalates, thiatrizene dioxides, isatoic anhydride, or anycombination thereof.

To facilitate the rate of crystallization, a crystallization nucleatingagent may also be present in the composition. A crystallizationnucleating agent generally enhances the initiation of crystallizationsites and induces crystallization of the polymeric material, therebyincreasing the rate of crystallization. Additionally, when anunencapsulated chemical blowing agent is present, a cell nucleatingagent generally provides initiating sites at which a blowing agent formsvoids in a foam composition. By selection of the cell nucleating agent,void sizes in the foam are better controlled (e.g., made smaller orlarger), as compared to without including the nucleating agent.Typically, when used, the one or more nucleating agents (e.g.,crystallization and/or cell nucleating agents) are present in an amountranging from 0.1 to 15 weight percent, inclusive, based on the totalweight of the composition.

Suitable nucleating agent(s) include for example inorganic minerals,organic compounds, salts of organic acids and imides, finely dividedcrystalline polymers with a melting point above the processingtemperature of the uncrosslinked thermoplastic matrix material, andcombinations of two or more of the foregoing. Combinations of two ormore different nucleating agents may also be used.

Examples of useful crystallization nucleating agents include, forexample, talc (hydrated magnesium silicate —H₂Mg₃(SiO₃)₄ orMg₃Si₄O₁₀(OH)₂), silica (SiO₂), titania (TiO₂), alumina (Al₂O₃), zincoxide, sodium salt of saccharin, calcium silicate, sodium benzoate,calcium titanate, aromatic sulfonate derivative, boron nitride, copperphthalocyanine, phthalocyanine, sodium salt of saccharin, isotacticpolypropylene, polybutylene terephthalate, and the like.

When an organic crystallization nucleating agent is present, thenucleating agent is typically at a concentration of at least 0.01, 0.02,0.03, 0.04, 0.05, 0.1, 0.15 or at least 0.2 wt. %, and ranging up toabout 1, 2, 3, 4 or 5 wt. % based on the total weight of thecomposition. When the nucleating agent is an inorganic oxide filler suchas silica, alumina, zinc oxide, and talc, the concentration can behigher.

In one embodiment, the crystallization nucleating agent may becharacterized as a salt of a phosphorous-containing aromatic organicacid such as zinc phenylphosphonate, magnesium phenylphosphonate,disodium 4-tert-butylphenyl phosponate, and sodium diphenylphosphinates.

One favored crystallization nucleating agent is zinc phenylphosphonatehaving the following chemical formula:

available from Nissan Chemical Industries, Ltd under the tradedesignation “Ecopromote”.

Examples of useful cell nucleating agents include, for example, talc,silica, silica particles functionalized with organic groups (e.g., anoctyl silane, a polyethylene glycol silane), glass beads, polymerparticles (e.g., starch (such as hydroxypropyl starch), polystyrene,polyvinyl pyrollidone (PVP)), mica, alumina, clay, calcium silicate,calcium titanate, calcium carbonate, and titania.

The compositions and articles may optionally contain one or moreconventional additives. Additives include, for example, antiblockadditives, cell stabilizers, surfactants, antioxidants, ultravioletabsorbers, lubricants, processing aids, antistatic agents, colorants,impact resistance aids, fillers, matting agents, flame retardants (e.g.zinc borate), pigments, and the like. Additional additives include, butare not limited to, carbon black, inorganic filler from micrometer sizeto nanosized, glass fibers, polymer fibers, or carbon fibers, etc.Suitable cell stabilizers include for instance and without limitationerucamide (i.e., (Z)-13-Docosenamide), and surface modified silicananoparticles. Surface modified silica nanoparticles may befunctionalized with an octyl silane or a polyethylene glycol silane, forexample. In certain embodiments, additional suitable surface modifiedsilica nanoparticles include those described in U.S. Pat. No. 6,586,483(Kolb et al.).

In some embodiments, inorganic fillers may be used as antiblockadditives to prevent blocking or sticking of layers or rolls of foamcompositions during storage and transport. Inorganic fillers includeclays and minerals, either surface modified or not. Examples includetalc, diatomaceous earth, silica, mica, kaolin, titanium dioxide,perlite, and wollastonite.

Hence, certain materials may potentially act as more than one of acrystallization nucleating agent, a cell nucleating agent, an antiblockadditive, a cell stabilizer, etc., in a composition.

Organic biomaterial fillers include a variety of forest and agriculturalproducts, either with or without modification. Examples includecellulose, wheat, starch, modified starch, chitin, chitosan, keratin,cellulosic materials derived from agricultural products, gluten, flour,and guar gum. The term “flour” concerns generally a composition havingprotein-containing and starch-containing fractions originating from oneand the same vegetable source, wherein the protein-containing fractionand the starch-containing fraction have not been separated from oneanother. Typical proteins present in the flours are globulins, albumins,glutenins, secalins, prolamins, glutelins. In typical embodiments, thecomposition comprises little or no organic biomaterial fillers such aflour. Thus, the concentration of organic biomaterial filler (e.g.flour) is typically less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or less than 1wt. % of the total foam composition.

Foam Compositions

In a second aspect, a foam composition is provided. The foam compositioncomprises: a closed cell foam thermoplastic nitrogen-containing matrixmaterial and an uncrosslinked thermoplastic material distributed in theclosed cell foam thermoplastic nitrogen-containing matrix material. Theclosed cell foam thermoplastic matrix material is formed by foaming theuncrosslinked thermoplastic matrix material described above with respectto the first aspect.

In some embodiments, the uncrosslinked thermoplastic material is presentas a plurality of particulates distributed (e.g., dispersed) in thefoam. The particulates are typically remnants of shells of the compositeparticles after they rupture during the foaming process. In certainembodiments, the uncrosslinked thermoplastic material is present as ablend with the closed cell foam thermoplastic nitrogen-containing matrixmaterial.

In some embodiments, the foam composition further comprises a pluralityof composite particles distributed in the closed cell foam thermoplasticnitrogen-containing matrix material (e.g., which did not rupture duringfoaming), wherein the composite particles each comprise: a chemicalblowing agent particle encapsulated within a shell comprising anuncrosslinked thermoplastic material, wherein the uncrosslinkedthermoplastic material exhibits a complex viscosity of 3,700 Pa·s orgreater at a decomposition temperature of the chemical blowing agentparticle. The composite particle is as described in detail above withrespect to the first aspect. In certain embodiments, 0.05 wt. % or more,0.1 wt. %, 0.15 wt. %, 0.25 wt. %, 0.5 wt. %, 0.75 wt. %, 1 wt. %, 1.5wt. %, or 2 wt. % or more of the composite particles remain (e.g.,intact) following foaming of the composition to form the foamcomposition; and 20 wt. % or less, 10 wt. %, 9.5 wt. %, 9 wt. %, 8.5 wt.%, 8 wt. %, 7.5 wt. %, 7 wt. %, 6.5 wt. %, 6 wt. %, 5.5 wt. %, 5 wt. %,4.5 wt. %, 4 wt. %, 3.5 wt. %, 3 wt. %, or 2.5 wt. % or less of thecomposite particles remain in the foam composition. Stated another way,the amount of composite particles remaining in the foam compositionfollowing foaming can range from 0.05 to 20 wt. % or 0.05 to 2.5 wt. %,of the total foam composition.

The foam composition comprises a closed cell foam, which means that thefoam contains substantially no connected cell pathways that extend fromone outer surface through the material to another outer surface. Aclosed cell foam can include up to about 10% open cells, within themeaning of “substantially” no connected cell pathways. Stated anotherway, the foam composition comprises 90% or greater closed cells, 92% orgreater closed cells, 95% or greater closed cells, or 98% or greaterclosed cells.

As mentioned above, it has been discovered that the preparation of foamcompositions including composite particles according to at least certainembodiments of the present disclosure resulted in decreased cell sizeand increased cell density and homogeneity upon foaming, as compared tothe cell size, density, and homogeneity upon foaming with unencapsulatedCBAs. Foam cells can be characterized by image analysis of across-section using scanning electron microscopy (SEM). Variousproperties of the foam compositions, as determined by the test methodsset forth in the examples, can include cell size, cell density, cellaspect ratio, and elastic modulus.

In certain embodiments, the foam composition comprises an average cellsize of 350 micrometers or less, 300, 250, 200, 150, 100, 80, 70, or 60micrometers or less; and 25 micrometers or greater, 30, 35, 40, 45, or50 micrometers or greater. In an embodiment, the foam composition has anaverage cell size of 30 to 65 micrometers. Further, in some embodiments,the foam composition comprises an average cell density of 1 cell persquare millimeter (cell/mm²) or greater, 2, 3, 4, 6, 8, 10, 12, 15, 20,25, 50, 75, 100, 125, 150, 200, 250, 300, 350, or 400 cells/mm² orgreater; and 1,000 cells/mm² or less, 950, 900, 850, 800, 750, 700, 650,600, 550, or 500 cells/mm² or less. Stated another way, the foamcomposition can have an average cell density of 1 to 1,000 cells/mm² or4 to 500 cells/mm².

For certain applications, a large average cell size is desirable, andthe foam composition can have an average cell size of 250 micrometers orgreater, 300, 350, 400, 450, 500, 550, or 600 micrometers or greater;and 1 millimeter (mm) or less, 950 micrometers, 900, 850, 800, 750, or700 micrometers or less. Stated another way, in certain embodiments thefoam composition can have an average cell size of 250 micrometers to 1mm.

When the foam composition is a monolithic sheet, the thickness of thesheet is typically at least 25, 50, or 100 micrometers (μm) (4 mils) to500 μm (20 mils) thickness. In some embodiments, the thickness of thefoam sheet is no greater than 10 mm, 5 mm, 2 mm, 400 μm, 300 μm, or nogreater than 200 μm. The foam may be in the form of individual sheets,particularly for a thickness of greater than 20 mils. The (e.g.,thinner) foam may be in the form of a roll-good.

Advantageously, foam compositions according to at least certainembodiments of the present disclosure provide a foam with a continuoussurface, whereas the same foam compositions prepared usingunencapsulated chemical blowing agents at equivalent weight percent ofblowing agent have a discontinuous surface. For instance, FIG. 3A showsan exterior surface of the foam sheet of Example 9, which does not haveholes visible on the surface (i.e., is continuous). In contrast, FIG. 3Bshows an exterior surface of the foam sheet of Comparative Example G,which does have visible holes 3010 on the surface (i.e., isdiscontinuous).

Foam compositions according to at least certain embodiments of thepresent disclosure provide a major surface having (e.g., a plurality of)replicated features. In select embodiments, the foam compositioncomprises a smooth major surface and an opposing major surfacecomprising replicated features. The replicated features can be raised orindented relative to the plane of the major surface, and have structuressuch as grooves, ridges, and various geometrical shapes. For instance,FIG. 6 shows a replicated surface of the foam composition of Example 23,having a raised tile pattern. Methods and apparatuses for forming areplicated surface on a major surface of a foam composition aredescribed in detail in co-owned PCT Publication Nos. WO 2019/064121(Slama et al.) and WO 2019/064120 (Meree et al.).

As used herein, a “smooth” surface is a surface that is free ofprotrusions and depressions that deviate from the plane of the surfaceat an angle of 25 degrees or greater and/or have a difference in heightof an average of 175 micrometers or greater. The foam composition can bebisected through the replicated structure and imaged (e.g., by scanningelectron microscopy (SEM)), and measurements taken on the image todetermine whether or not the opposing surface is smooth. First, an idealline is added along the surface to be analyzed, then angle and heightdeviations are measured from the ideal line and the actual line ofprotrusion and/or depression.

For instance, FIG. 8A shows a cross-section of the foam composition 8002of Example 23 having a replicated major surface 8004, which wasdetermined to have a smooth opposing major surface 8006. This is due tomeasuring an angle of 6 degrees at a first deviation 8010 (from ideal),an angle of 3.9 degrees at a second deviation 8012, and an averageheight of 18 micrometers over the length 8011 from the first deviation8010 through the second deviation 8012; an angle of 6.3 degrees at athird deviation 8014, an angle of 11.6 degrees at a fourth deviation8016, and an average height of 52 micrometers over the length 8015 fromthe third deviation 8014 through the fourth deviation 8016; an angle of9.1 degrees at a fifth deviation 8018, an angle of 2.6 degrees at asixth deviation 8020, and an average height of 21 micrometers over thelength 8019 from the fifth deviation 8018 through the sixth deviation8020. The three shallow, relatively flat deviations allow the opposingmajor surface 8006 to be considered smooth.

Similarly, FIG. 8B shows a cross-section of the foam composition 8102 ofExample 22 having a replicated major surface 8104, which was determinedto have a smooth opposing major surface 8106. This is due to measuringan angle of 7.3 degrees at a first deviation 8110 (from ideal), an angleof 6.7 degrees at a second deviation 8112, and an average height of 145micrometers over the length 8111 from the first deviation 8110 throughthe second deviation 8112. Although the foam composition 8102 has a deepdepression, the topology changes gradually and allows the opposing majorsurface 8106 to be considered smooth. In contrast, FIG. 8C shows across-section of the foam composition 8202 of Comparative Example Ghaving a replicated major surface 8204, which was determined to have arough (e.g., not smooth) opposing major surface 8206. This is due tomeasuring an angle of 57.3 degrees at a first deviation 8210 (fromideal), an angle of 66.3 degrees at a second deviation 8212, and anaverage height of 73 micrometers over the length 8211 from the firstdeviation 8210 through the second deviation 8212; an angle of 17.4degrees at a third deviation 8214, an angle of 66.3 degrees at a fourthdeviation 8216, and an average height of 52 micrometers over the length8215 from the third deviation 8214 through the fourth deviation 8216;and an angle of 33.3 degrees at a fifth deviation 8218, an angle of 72.2degrees at a sixth deviation 8220, and an average height of 479micrometers over the length 8219 from the fifth deviation 8218 throughthe sixth deviation 8220. The opposing major surface 8206 of the foamcomposition of Comparative Example G has a deep depression with jaggededges and as well as small jagged protrusions, and is not smooth.

Process of Making a Foam Composition

In a fourth aspect, a method of making a foam composition is provided.The method comprises a) compressing a mixture comprising: anuncrosslinked thermoplastic nitrogen-containing matrix material and aplurality of composite particles distributed in the uncrosslinkedthermoplastic nitrogen-containing matrix material; and b) heating thecompressed mixture, thereby forming the foam composition. The mixtureexhibits an elastic modulus of 0.5 megaPascals (MPa) or greater. Theplurality of composite particles each comprises a chemical blowing agentparticle encapsulated within a shell comprising an uncrosslinkedthermoplastic material, wherein the uncrosslinked thermoplastic materialexhibits a complex viscosity of 3,700 Pa·s or greater at a decompositiontemperature of the chemical blowing agent particle.

Optionally, the method further comprises casting the mixture into areplication mold while the heated mixture is forming the foamcomposition, thereby imparting a plurality of replicated features on amajor surface of the foam composition.

In preparing a composition as described herein, the components (e.g.,uncrosslinked thermoplastic matrix material, composite particles, andother optional components) are heated (e.g., subjected to a temperatureranging from 90° C.-220° C., inclusive) and thoroughly mixed using anysuitable means known by those of ordinary skill in the art. For example,the composition may be mixed by use of a (e.g., Brabender) mixer,extruder, kneader or the like.

In certain embodiments, the mixture may be prepared into the form ofpellets, such as by extruding and pelletizing at least a portion of themixture. One advantage to the mixture comprising a plurality of pelletsis a greater ease of handling the mixture than certain alternate formsof mixtures.

Upon heating the mixture, the chemical blowing agent of the compositeparticle assists in generating voids to form the foam composition. Insome embodiments, more than one blowing agent may be used in certainfoam compositions, and in addition to the composite particles, theblowing agent may comprise an unencapsulated chemical blowing agent, anunencapsulated physical blowing agent, expandable microspheres, or acombination thereof. Useful categories of blowing agents include, forinstance, a volatile liquid, a gas, a chemical compound, and a pluralityof expandable microspheres. Volatile liquid and gas blowing agentsexpand when heated and then tend to escape from the mixture, leavingvoids behind, to form the foam composition. Chemical compound blowingagents decompose and at least a portion of the decomposition product(s)expand and then escape from the mixture, leaving voids behind. In someembodiments, the blowing agent comprises a plurality of expandablemicrospheres, which are described above.

Suitable unencapsulated chemical blowing agents include for instance andwithout limitation, an azo compound, a diazocompound, a sulfonylhydrazide, a tetrazole, a nitrosocompound, an acyl sulfonyl hydrazide,hydrazones, thiatriazoles, azides, sulfonyl azides, oxalates,thiatrizene dioxides, isotaoic anhydride, or any combination thereof.Examples of suitable unencapsulated chemical blowing agents include forinstance and without limitation, 1,1-azodicarboxamide, p-toluenesulfonyl hydrazide, p-toluenesulfonyl semicarbazide, and 5H-phenyltetrazole. In some embodiments, preferred compounds include, forexample, 1,1-azodicarbonamide, azodiisobutyro-nitrile,benzenesulfonhydrazide, and hydrazo dicarbonamide.

Various methods for preparing foam compositions are suitable for atleast certain embodiments of the method. More particularly, the methodmay include compressing the mixture in a melt press and/or an extruder,and may include heating the compressed mixture in a mold, an oven,and/or an extruder. In certain embodiments, the mixture is compressed inan extruder, heated in an extruder, or both compressed and heated in anextruder. Typically, an extruder comprises at least a barrel, a necktube, and a die. Some suitable single screw and twin screw extruders aredescribed in the examples below. In select embodiments, the extruder isa multilayer extruder, through which one or more foam layers may beformed, e.g., using a multilayer die. In certain embodiments, thecompressed mixture is heated at ambient pressure. The compressed mixtureis heated, typically by subjection to a temperature of 40° C. orgreater, 50° C., 60° C., 75° C., 90° C., 100° C., 120° C., 130° C., 140°C., 150° C., 160° C., 170° C., or 180° C. or greater; and 500° C. orless, 475° C., 450° C., 425° C., 400° C., 375° C., 350° C., 325° C.,300° C., 275° C., 250° C., 230° C., 210° C., 200° C., 190° C., 180° C.;such as ranging from 40° C. to 475° C., 40° C. to 350° C., 140° C. to310° C., or 180° C. to 300° C., inclusive.

Optionally, the mixture further comprises at least one physical blowingagent, such as a volatile liquid and/or expandable microspheres.

Articles

In a third aspect, an article is provided. The article includes the foamcomposition according to the second aspect (e.g., closed cell foam)described in detail above. In some embodiments, the article is amultilayer article and the foam composition is a layer of foam disposedin between a layer of a second material and a layer of a third material.For instance, FIG. 4A shows an SEM image of a three-layer article 4002according to Example 20, sliced in the transverse direction, the articlehaving a core foam layer 4010, a top (non-foam) layer 4012 and a bottom(non-foam) layer 4014. Similarly, FIG. 4B shows an SEM image of thethree-layer article 4002 according to Example 20, sliced in the machinedirection, the article having a core foam layer 4010, a top (non-foam)layer 4012 and a bottom (non-foam) layer 4014. In this example, theclosed foam cells 4016 are a little more elongated when viewed from themachine direction than from the transverse direction. Optionally, one ormore of the second material or third material in a multilayer article isalso a foam material.

An article including a foam composition attached to a substrate providesfor use of the foam composition in cushioning or polishing applications,for instance.

When the article is a monolithic sheet, the thickness of the sheet istypically at least 25, 50, 100 micrometers (μm) (4 mils), or at least500 μm (20 mils) in thickness. In some embodiments, the thickness of thearticle is no greater than 10 mm, 5 mm, 2 mm, 400 μm, 300 μm, or 200 μm.

Exemplary uses of foam compositions (e.g., polymeric foam layers)described herein include vibration damping and polishing applications(e.g., polishing pads useful in chemical mechanical planarization(CMP)). In an eighth aspect, a polishing pad is provided.

Further to CMP polishing applications, the polishing pad thickness maycoincide with the required thickness to enable polishing on theappropriate polishing tool. In some embodiments, the polishing padthickness is greater than 125 (in some embodiments, greater than 150,200 or even greater than 500; in some, less than 40,000, 30,000, 20,000,15,000, 10,000, 5,000 or even less than 2,500) micrometers. Thepolishing pad may be in any of a variety of shapes (e.g., circular,square, or hexagonal). The pads may be fabricated such that the padshape coincides with the shape of the corresponding platen of thepolishing tool the pad will be attached to during use. The maximumdimension of the pad (e.g., the diameter for a circular shaped pad) canbe as desired for a particular application. In some embodiments, themaximum dimension of a pad is at least 10 cm (in some embodiments, atleast 20 cm, 25 cm, 30 cm, 40 cm, 50 cm, or even, at least 60 cm; insome embodiments, less than 2 meters, 1.5 meter, or even less than 1meter).

In some polishing pad embodiments, the foam features extend from or intothe first major surface by at least 100 micrometers (in someembodiments, at least 200 micrometers or even by at least 300micrometers; in some embodiments, up to 20,000 micrometers, 15,000micrometers, 10,000 micrometers or even up to 5,000 micrometers).

A foam composition layer of the polishing pad may further include atleast one channel, wherein the channel has a depth greater than thedistance the foam features extend from or into the first major surface.In some embodiments, the foam composition of the polishing pad mayfurther include at least a plurality of channels, wherein at least aportion of the plurality of channels has a depth greater than thedistance the foam features extend from or into the first major surface.The at least one channel may provide improved polishing solutiondistribution, foam composition flexibility, as well as facilitate swarfremoval from the polishing pad. In some embodiments, the channels do notallow fluid to be contained indefinitely within the channel (i.e., fluidcan flow out of the channel during use of the pad).

In some embodiment, the width of the at least one channel is at least 10(in some embodiments, at least 25, 50, 75, or even at least 100; in someembodiments less than 20,000, 10,000, 5,000, 2,000, 1,000, 500, or evenless than 200) micrometers. In some embodiments, the depth of the atleast one channel is at least 125 (in some embodiments, at least 200,300, 400, 500, 600, 700, 800, 900, 1,000, 1500, or even at least 2,000;in some embodiments, less than 25,000, 20,000, 15,000, 10,000, 8,000,5,000, 3,000, or even less than 1,000) micrometers.

The channels may be formed into the polishing layer by any knowntechniques in the art including, but not limited to, machining,embossing and molding. The channels may be formed during the formationof the foam composition and/or by the same process used to form the foamcomposition layer. Due to improved surface finish on the first majorsurface of the polishing foam layer (which helps minimize substratedefects (e.g., scratches during use)), embossing and molding may bepreferred. In some embodiments, the channels extending from or into thefirst major surface of the foam composition layer are fabricated in themolding process used to form the foam features. This is achieved byforming their negative (i.e., raised regions) in the tool roll, with thechannels themselves then being formed in the foam composition duringmolding. This is of particular advantage, as the foam features extendingfrom or into the first major surface of the foam composition layer andthe at least one channel may be fabricated into the polishing foam layerin a single process step, leading to cost and time savings. The channelscan be fabricated to form various patterns known in the art (e.g.,concentric rings, parallel lines, radial lines, a series of linesforming a grid array, herring bone, and spiral). Combinations ofdiffering patterns may be used.

In yet another embodiment, the polishing pad of the present disclosuremay include a subpad, wherein the subpad is adjacent to the second majorsurface of the foam composition layer. The polishing pad layers (e.g.,polymeric foam layer and subpad, may be adhered together by anytechniques known in the art (including using adhesives (e.g., pressuresensitive adhesives (PSAs), hot melt adhesives and cure in placeadhesives)). In some embodiments, the polishing pad includes an adhesivelayer adjacent to the second major surface of the foam compositionlayer. Use of a lamination process in conjunction with PSAs (e.g., PSAtransfer tapes) is one particular process for adhering the polishing padand subpad. The subpad may be any of those known in the art. The subpadmay be a single layer of a substantially rigid material (e.g.,polycarbonate) or a single layer of a substantially compressiblematerial (e.g., an elastomeric foam). The subpad may also have at leasttwo layers, and may include a substantially rigid layer (e.g., a stiffmaterial or high modulus material (e.g., polycarbonate or polyester))and a substantially compliant layer (e.g., an elastomer or anelastomeric foam material). If the subpad includes a substantiallycompliant layer (e.g., an elastomeric foam layer, the compliant layermay have a durometer in a range from 20 Shore D to 90 Shore D). In someembodiments, the compliant layer has a thickness in a range from 125 to5,000 (in some embodiments, in a range from 125 to 1000) micrometers.

In some embodiments of polishing pads that include a subpad having atleast one opaque layer, a small (e.g., 1 cm to 5 cm) hole may be cutinto the subpad creating a “window”. The hole may be cut through theentire subpad or only through at least one opaque layer. The cut portionof the subpad or at least one opaque layer is removed from the subpad,allowing light to be transmitted through this region. The hole ispre-positioned to align with the endpoint window of the polishing toolplaten and facilitates the use of the wafer endpoint detection system ofthe polishing tool, by enabling light from the tool's endpoint detectionsystem to travel through the polishing pad and contact the wafer.Light-based endpoint polishing detection systems are known in the artand are available, for example, under the trade designations “MIRRA” and“REFLEXION LK CMP” from Applied Materials, Inc., Santa Clara, Calif.Polishing pads described herein can be fabricated to run on such toolsand endpoint detection windows, which are configured to function withthe polishing tool's endpoint detection system, can be included in thepolishing pad.

In some embodiments, a polishing pad described herein includes subpadlaminated thereto. The subpad can include at least one rigid layer(e.g., polycarbonate) and at least one compliant layer (e.g., anelastomeric foam, the elastic modulus of the rigid layer being greaterthan the elastic modulus of the compliant layer). The rigid layer may belaminated to the second major surface of the foam composition layer,typically through the use of a PSA (e.g., transfer adhesive or tape).The compliant layer may be opaque and prevent light transmissionrequired for endpoint detection. Prior to, or after lamination, a hole(e.g., up to 5 cm wide by 20 cm long) may be die cut, for example, by astandard kiss cutting method or cut by hand, in the opaque compliantlayer of the subpad. The cut region of the compliant layer is removedcreating a “window” in the polishing pad. If adhesive residue is presentin the hole, it can be removed, for example, through the use, forexample, of an appropriate solvent and/or wiping with a cloth. The“window” in the polishing pad is configured such that, when thepolishing pad is mounted to the polishing tool platen, the window of thepolishing pad aligns with the endpoint detection window of the polishingtool platen. The dimensions of the hole are generally the same orsimilar in dimension to the dimensions of the endpoint detection windowof the platen.

The polishing pad, including any one of foam composition layers, thesubpad and any combination thereof, may include a window (i.e., a regionallowing light to pass through) to enable standard endpoint detectiontechniques used in polishing processes (e.g. wafer endpoint detection).

In a ninth aspect, the present disclosure also describes a polishingsystem comprising at least one polishing pad and at least one polishingsolution. Suitable polishing solutions are known in the art. Thepolishing solutions may be aqueous or non-aqueous. An aqueous polishingsolution has at least 50% by weight water. A non-aqueous solution hasless than 50% by weight water. In some embodiments, the polishingsolution is a slurry (i.e., a liquid that contains organic and/orinorganic abrasive particles). The concentration of organic and/orinorganic abrasive particles in the polishing solution is as desired. Insome embodiments, the concentration of organic and/or inorganic abrasiveparticles in the polishing solution is at least 0.5% (in someembodiments, at least 1%, 2%, 3%, 4%, or even at least 5%; in someembodiments, less than 30%, 20%, 15%, or even less than 10%) by weight.In some embodiments, the polishing solution is substantially free oforganic and/or inorganic abrasive particles. By “substantially free oforganic or inorganic abrasive particles,” it is meant that the polishingsolution contains not greater than 0.5% (in some embodiments, notgreater than 0.25%, 0.1%, or even not greater than 0.05%) by weight oforganic and/or inorganic abrasive particles. In some embodiments, thepolishing solution contain no organic and no inorganic abrasiveparticles. The polishing system may include polishing solutions (e.g.,slurries, used for silicon oxide CMP (e.g., shallow trench isolationCMP), metal CMP (e.g., tungsten CMP, copper CMP, and aluminum CMP),barrier CMP (e.g., tantalum and tantalum nitride CMP), and hardsubstrates (e.g., sapphire). In some embodiments, the polishing systemfurther comprises a substrate to be polished or abraded.

In a tenth aspect, the present disclosure also describes a method ofpolishing a substrate, the method comprising:

providing a polishing pad described herein having a working surface;

providing a substrate having a first surface;

contacting the first working surface of the polishing pad with the firstsubstrate surface; and

moving the polishing pad and the substrate relative to one another whilemaintaining contact between the working surface of the polishing pad andthe first substrate surface, wherein polishing is conducted in thepresence of a polishing solution.

In some embodiments, the polishing solution is a slurry as previouslydescribed herein. In some embodiments, the substrate is a semiconductorwafer. Exemplary semiconductor wafers comprise at least one of adielectric material, an electrically conductive material, a barrierand/or adhesion material or a cap material. Exemplary dielectricmaterials include an inorganic dielectric material (e.g., glass (e.g.,silica glasses)) or an organic dielectric material. Exemplaryelectrically conductive materials include metals (e.g., at least one ofcopper, tungsten, aluminum, or silver). Exemplary cap materials includeat least one of silicon carbide or silicon nitride. Exemplary barrierand/or adhesion materials include at least one of tantalum or tantalumnitride. The method of polishing may also include a pad conditioning orcleaning step, which may be conducted in-situ (i.e., during polishing).Pad conditioning may use any pad conditioner (e.g., a diamond padconditioner), or brush known in the art and is available, for example,under the trade designations “3M CMP PAD CONDITIONER BRUSH PB33A” fromthe 3M Company, St. Paul, Minn., and/or a water or solvent rinse of thepolishing pad.

Various embodiments are provided that include foam compositions,articles, composite particles, polishing pads, polishing systems, andmethods of making and using same.

Embodiment 1 is a composition. The composition includes an uncrosslinkedthermoplastic nitrogen-containing matrix material and a plurality ofcomposite particles distributed in the uncrosslinked thermoplasticnitrogen-containing matrix material. The composition exhibits an elasticmodulus of 0.5 MPa or greater. The plurality of composite particles eachincludes a chemical blowing agent particle encapsulated within a shellincluding an uncrosslinked thermoplastic material. The uncrosslinkedthermoplastic material exhibits a complex viscosity of 3,700 Pa·s orgreater at a decomposition temperature of the chemical blowing agentparticle.

Embodiment 2 is the composition of embodiment 1, wherein theuncrosslinked thermoplastic nitrogen-containing matrix materialcomprises a polyamide, a polyurethane, a polyethyleneimine, a polyimide,a polyurea, a polyoxazoline, a polyiminothioether, a polyaminoamide, apolysulfonamide, or combinations thereof.

Embodiment 3 is the composition of embodiment 1 or embodiment 2, whereinthe uncrosslinked thermoplastic nitrogen-containing matrix materialincludes a polyurethane.

Embodiment 4 is the composition of any of embodiments 1 to 3, where theuncrosslinked thermoplastic nitrogen-containing matrix materialsincludes a polyether-based thermoplastic polyurethane.

Embodiment 5 is the composition of any of embodiments 1 to 4, where theuncrosslinked thermoplastic nitrogen-containing matrix material includesa polyester-based thermoplastic polyurethane.

Embodiment 6 is the composition of any of embodiments 1 to 3, whereinthe uncrosslinked thermoplastic nitrogen-containing matrix materialincludes a polyamide.

Embodiment 7 is the composition of any of embodiments 1 to 6, whereinthe polyamide is acid-terminated.

Embodiment 8 is the composition of any of embodiments 1 to 6, whereinthe polyamide is amine-terminated.

Embodiment 9 is the composition of any of embodiments 1 to 8, whereinthe uncrosslinked thermoplastic nitrogen-containing matrix materialexhibits a softening point of 40° C. to 220° C.

Embodiment 10 is the composition of any of embodiments 1 to 9, furtherincluding a crosslinking agent, a crosslink catalyst, or both.

Embodiment 11 is the composition of embodiment 10, wherein thecrosslinking agent includes a multifunctional epoxide, a polyfunctionalaziridine, a glycidyl epoxy resin, an isocyanate, a bismaleimide, amultifunctional acrylate, a cycloaliphatic epoxy resin, or apolycarbodiimide.

Embodiment 12 is the composition of embodiment 10 or embodiment 11,wherein the crosslink catalyst includes an alkyl or alkenyl ammonium,phosphonium, or imidazolium salt.

Embodiment 13 is the composition of any of embodiments 1 to 12, whereinthe uncrosslinked thermoplastic nitrogen-containing matrix materialexhibits a modulus of 0.5 megapascals (MPa) to 5,000 MPa or 0.05 to2,000 MPa.

Embodiment 14 is the composition of any of embodiments 1 to 13, furtherincluding a crystallization nucleating agent, an antiblock additive, acell stabilizer, a surfactant, or a combination thereof.

Embodiment 15 is the composition of any of embodiments 1 to 14, whereinthe plurality of composite particles is present in an amount of 0.1 to20 wt. %, 0.5 to 15 wt. %, 0.5 wt. % to 10 wt. %, 1 to 8 wt. %, or 10 to17 wt. %, inclusive, of the total composition.

Embodiment 16 is the composition of any of embodiments 1 to 15, whereinthe chemical blowing agent is selected from a diazocompound, a sulfonylhydrazide, a tetrazole, a nitrosocompound, an acyl sulfonyl hydrazide,hydrazones, thiatriazoles, azides, sulfonyl azides, oxalates,thiatrizene dioxides, isatoic anhydride, or combinations thereof.

Embodiment 17 is the composition of any of embodiments 1 to 16, whereinthe chemical blowing agent is 1,1-azodicarboxamide, a hydrazide-basedchemical blowing agent-, p-toluenesulfonyl semicarbazide or 5H-phenyltetrazole.

Embodiment 18 is the composition of any of embodiments 1 to 17, whereinthe chemical blowing agent is 1,1-azodicarboxamide.

Embodiment 19 is the composition of any of embodiments 1 to 18, whereinthe chemical blowing agent is p-toluene sulfonyl hydrazide.

Embodiment 20 is the composition of any of embodiments 1 to 19, whereinthe chemical blowing agent is 5H-phenyl tetrazole.

Embodiment 21 is the composition of any of embodiments 1 to 20, whereinthe chemical blowing agent is p-toluenesulfonyl semicarbazide.

Embodiment 22 is the composition of any of embodiments 1 to 21, whereinthe uncrosslinked thermoplastic material is selected from a starch,polyvinyl pyrollidinone (PVP), a copolymer of vinylpyrrolidone and vinylacetate, a polypropylene-based elastomer, a styrene-isoprene-styrenecopolymer, a (C₁-C₃)alkyl cellulose, a hydroxyl (C₁-C₃)alkylcellulose,carboxy methylcellulose, sodium carboxymethyl cellulose, apolyoxazoline, a silicone-based thermoplastic polymer, an olefin-basedthermoplastic polymer, a phenoxy resin, a polyamide, or combinationsthereof.

Embodiment 23 is the composition of any of embodiments 1 to 22, whereinthe uncrosslinked thermoplastic material is selected from hydroxylatedstarch, carboxylated starch, methyl cellulose, propyl cellulose, ethylcellulose, hypromellose, hydroxypropylmethyl cellulose, hydroxypropylcellulose, hydroxyethyl cellulose, or combinations thereof.

Embodiment 24 is the composition of any of embodiments 1 to 23, whereinthe uncrosslinked thermoplastic material is selected from hydroxypropylstarch, PVP, a polyamide, a styrenic copolymer, or a combinationthereof.

Embodiment 25 is the composition of any of embodiments 1 to 24, whereinthe uncrosslinked thermoplastic material includes hydroxypropyl starch.

Embodiment 26 is the composition of any of embodiments 1 to 25, whereinthe uncrosslinked thermoplastic material exhibits a complex viscosity of5,000 Pa·s or greater or 6,000 Pa·s or greater at a decompositiontemperature of the chemical blowing agent particle.

Embodiment 27 is the composition of any of embodiments 1 to 26, whereinthe plurality of composite particles has an average diameter of 1 to 60micrometers, inclusive.

Embodiment 28 is the composition of any of embodiments 1 to 27, whereinthe plurality of composite particles further includes a co-encapsulatedmetal oxide or metal salt, or mixtures thereof.

Embodiment 29 is the composition of embodiment 28, wherein the metaloxide is selected from zinc oxide, calcium oxide, and barium-cadmiumcomplex; and the metal salts are of the form MX or M(X)₂, wherein M isselected from zinc, calcium, cadmium, potassium, barium, strontium,magnesium, mercury, titanium, tin, lead, sodium, lithium, or cesium, andwherein X is an organic ligand or an inorganic ligand containing anitrate, phosphate, phosphite, sulfate, carbonate, oxalic acid, halide,para-toluenesulfonate, tetrafluoroborate, perchlorate, hydroxide, orcyanide moiety, or the corresponding hydrates.

Embodiment 30 is the composition of embodiment 28 or embodiment 29,wherein the metal salt is zinc stearate, zinc nitrate, zinc sulfate,zinc phosphate, zinc chloride, zinc bromide, zinc iodide, zinc fluoride,zinc carbonate, zinc p-toluenesulfonate hydrate, zinc tetrafluoroboratehydrate, zinc perchlorate, zinc hydroxide, zinc cyanide, calciumnitrate, calcium sulfate, calcium phosphate, calcium carbonate, bariumphosphate, barium nitrate, barium sulfate, cadmium phosphate, cadmiumnitrate, cadmium sulfate, calcium stearate, barium-cadmium stearate,zinc 2-ethyl hexanoate, calcium 2-ethyl hexanoate, barium-cadmium2-ethyl hexanoate, zinc acetate, calcium acetate, zinc malonate, calciummalonate, zinc benzoate, calcium benzoate, zinc salicylate, calciumsalicylate, cadmium bromide, cadmium carbonate, cadmium chloride,cadmium iodide, or cadmium perchlorate.

Embodiment 31 is the composition of any of embodiments 28 to 30, whereinthe metal oxide, the metal salt, or combinations thereof, is present inan amount of 500 wt. % or less of the amount of the chemical blowingagent, 300 wt. % or less, 100 wt. % or less, or 25 wt. % or less of theamount of the chemical blowing agent.

Embodiment 32 is the composition of any of embodiments 28 to 31, whereinthe chemical blowing agent is 1,1-azodicarboxamide or p-toluene sulfonylhydrazide.

Embodiment 33 is the composition of any of embodiments 28 to 32, whereinthe plurality of composite particles further includes a co-encapsulatedpolyhydroxyl compound, an amine containing compound, or a carboxylicacid containing compound.

Embodiment 34 is the composition of embodiment 33, wherein thepolyhydroxyl compound is selected from glycerol, ethylene glycol,diethylene glycol, triethylene glycol, or combinations thereof.

Embodiment 35 is the composition of embodiment 33 or embodiment 34,wherein the carboxylic acid containing compound is selected from stearicacid, 2-ethylhexanoic acid, acetic acid, palmitic acid, or combinationsthereof.

Embodiment 36 is the composition of any of embodiments 33 to 35, whereinthe amine containing compound is a primary amine.

Embodiment 37 is the composition of any of embodiments 33 to 36, whereinthe chemical blowing agent is p-toluene sulfonyl hydrazide.

Embodiment 38 is a foam composition. The foam composition includes aclosed cell foam thermoplastic nitrogen-containing matrix material andan uncrosslinked thermoplastic material distributed in the closed cellfoam thermoplastic nitrogen-containing matrix material.

Embodiment 39 is the foam composition of embodiment 38, wherein theuncrosslinked thermoplastic material is present as a plurality ofparticulates.

Embodiment 40 is the foam composition of embodiment 38 or embodiment 39,further including a plurality of composite particles distributed in theclosed cell foam thermoplastic nitrogen-containing matrix material. Theplurality of composite particles each includes a chemical blowing agentparticle encapsulated within a shell including an uncrosslinkedthermoplastic material. The uncrosslinked thermoplastic materialexhibits a complex viscosity of 3,700 Pa·s or greater at a decompositiontemperature of the chemical blowing agent particle.

Embodiment 41 is the foam composition of embodiment 38 or embodiment 40,wherein the uncrosslinked thermoplastic material is present as a blendwith the closed cell foam thermoplastic nitrogen-containing matrixmaterial.

Embodiment 42 is the foam composition of any of embodiments 38 to 41,wherein an outer major surface of the foam composition has a continuoussurface.

Embodiment 43 is the foam composition of any of embodiments 38 to 42,wherein the foam composition comprises a smooth major surface and anopposing major surface comprising replicated features.

Embodiment 44 is the foam composition of any of embodiments 38 to 43,having 90% or greater closed cells, 95% or greater, or 98% or greaterclosed cells.

Embodiment 45 is the foam composition of any of embodiments 38 to 44,having an average cell size of 250 micrometers or less, 150 micrometersor less, 120 micrometers or less, 100 micrometers or less, 80micrometers or less, or 60 micrometers or less.

Embodiment 46 is the foam composition of any of embodiments 38 to 45,having an average cell size of 30 micrometers to 65 micrometers.

Embodiment 47 is the foam composition of any of embodiments 38 to 44,having an average cell size of 250 micrometers to 1 millimeter.

Embodiment 48 is the foam composition of any of embodiments 38 to 47,wherein the thermoplastic nitrogen-containing matrix material includes apolyamide, a polyurethane, a polyetherimine, a polyimide, apoly(ester)amide, a polyetherimide, a polyurea, a polyoxazoline, apolyiminothioether, a polyaminoamide, a polysulfonamide, apoly(amide-imide), or combinations thereof.

Embodiment 49 is the foam composition of any of embodiments 38 to 48,wherein the thermoplastic nitrogen-containing matrix material includes apolyurethane.

Embodiment 50 is the foam composition of any of embodiments 38 to 49,wherein the thermoplastic nitrogen-containing matrix material includes apolyamide.

Embodiment 51 is the foam composition of any of embodiments 38 to 50,wherein the uncrosslinked thermoplastic material is selected from astarch, polyvinyl pyrollidinone (PVP), a copolymer of vinylpyrrolidoneand vinyl acetate, a polypropylene-based elastomer, astyrene-isoprene-styrene copolymer, a (C₁-C₃)alkyl cellulose, a hydroxyl(C₁-C₃)alkylcellulose, carboxy methylcellulose, sodium carboxymethylcellulose, a polyoxazoline, a silicone-based thermoplastic polymer, anolefin-based thermoplastic polymer, a phenoxy resin, a polyamide, orcombinations thereof.

Embodiment 52 is the foam composition of any of embodiments 38 to 51,wherein the uncrosslinked thermoplastic material is selected fromhydroxypropyl starch and PVP.

Embodiment 53 is the foam composition of any of embodiments 38 to 52,wherein the foam composition has a cell density of 1 to 1,000 cells persquare millimeter (cells/mm²) or 4 to 500 cells/mm².

Embodiment 54 is an article. The article includes the foam compositionof any of claims 38 to 53 attached to a substrate.

Embodiment 55 is the article of embodiment 54, wherein the article is amultilayer article and the foam composition is a layer of foam disposedin between a layer of a second material and a layer of a third material.

Embodiment 56 is the article of embodiment 55, wherein at least one ofthe second material and the third material includes a foam material.

Embodiment 57 is the article of any of embodiments 54 to 56, wherein atleast one major surface includes a plurality of replicated features.

Embodiment 58 is a method of making a foam composition of any ofembodiments 38 to 52. The method includes a) compressing a mixture; andb) heating the compressed mixture, thereby forming the foam composition.The mixture includes an uncrosslinked thermoplastic nitrogen-containingmatrix material and a plurality of composite particles distributed inthe uncrosslinked thermoplastic nitrogen-containing matrix material. Themixture exhibits an elastic modulus of 0.5 MPa or greater. The pluralityof composite particles each includes a chemical blowing agent particleencapsulated within a shell including an uncrosslinked thermoplasticmaterial. The uncrosslinked thermoplastic material exhibits a complexviscosity of 3,700 Pa·s or greater at a decomposition temperature of thechemical blowing agent particle.

Embodiment 59 is the method of embodiment 58, wherein the mixture iscompressed in a melt press.

Embodiment 60 is the method of embodiment 58 or embodiment 59, whereinthe compressed mixture is heated in a mold.

Embodiment 61 is the method of any of embodiments 58 to 60, wherein thecompressed mixture is heated in an oven.

Embodiment 62 is the method of any of embodiments 58 to 61, wherein thecompressed mixture is heated at ambient pressure.

Embodiment 63 is the method of any of embodiments 58 to 62, wherein themixture is compressed in an extruder.

Embodiment 64 is the method of any of embodiments 58 or 63, wherein thecompressed mixture is heated in an extruder.

Embodiment 65 is the method of embodiment 63 or embodiment 64, whereinthe extruder is a multilayer extruder.

Embodiment 66 is the method of any of embodiments 63 to 65, furtherincluding casting the mixture into a replication mold while the heatedmixture is forming the foam composition, thereby imparting a pluralityof replicated features on a major surface of the foam composition.

Embodiment 67 is the method of any of embodiments 58 to 66, wherein thecompressed mixture is heated at a temperature ranging from 40° C. to350° C.

Embodiment 68 is the method of any of embodiments 58 to 67, wherein thecompressed mixture is heated at a temperature ranging from 140° C. to310° C.

Embodiment 69 is the method of any of embodiments 58 to 68, wherein thecompressed mixture is heated at a temperature ranging from 140° C. to305° C.

Embodiment 70 is a composite particle. The composite particle includes achemical blowing agent particle encapsulated within a shell including anuncrosslinked thermoplastic material; and a co-encapsulated metal salt.The metal salt is of the form MX or M(X)₂, wherein M is zinc, calcium,cadmium, potassium, barium, strontium, magnesium, mercury, titanium,tin, lead, sodium, lithium, or cesium, and wherein X is an organicligand or an inorganic ligand containing a nitrate, phosphate,phosphite, sulfate carbonate, oxalic acid, halide,para-toluenesulfonate, tetrafluoroborate, perchlorate, hydroxide, orcyanide moiety, or the corresponding hydrates. The uncrosslinkedthermoplastic material exhibits a complex viscosity of 3,700 Pascalseconds (Pa·s) or greater at a decomposition temperature of the chemicalblowing agent particle.

Embodiment 71 is the composite particle of embodiment 70, wherein themetal salt includes zinc nitrate, zinc sulfate, zinc phosphate, zincchloride, zinc carbonate, zinc p-toluenesulfonate hydrate, zinctetrafluoroborate hydrate, zinc perchlorate, zinc hydroxide, zinccyanide, calcium nitrate, calcium sulfate, calcium phosphate, calciumcarbonate, barium phosphate, barium nitrate, barium sulfate, cadmiumphosphate, cadmium nitrate, cadmium sulfate, or combinations thereof.

Embodiment 72 is the composite particle of embodiment 70 or embodiment71, wherein the metal salt includes zinc nitrate, zinc sulfate, or zincchloride.

Embodiment 73 is a composition. The composition includes anuncrosslinked thermoplastic matrix material and a plurality of thecomposite particles of any embodiments 70 to 72 distributed in theuncrosslinked thermoplastic matrix material.

Embodiment 74 is the composition of claim 73, wherein the uncrosslinkedthermoplastic matrix material is selected from a polyorganosiloxane, astyrenic block copolymer, a styrenic polymer, a polystyrene, apolyolefin, a polyolefin copolymer, polyvinyl chloride (PVC), ethylenevinyl acetate, polyacrylate, polymethacrylate, an acrylate copolymer,and an acrylic block copolymer.

Embodiment 75 is the composition of embodiment 73, wherein theuncrosslinked thermoplastic matrix material includes a polylactic acid(PLA). The composition further includes a polymer having a T_(g) of 25degrees Celsius or greater; a crosslinking agent; and a crosslinkcatalyst.

Embodiment 76 is a foam composition. The foam composition includes aclosed cell foam thermoplastic matrix material and a plurality of thecomposite particles of any embodiments 70 to 72 distributed in theclosed cell foam thermoplastic matrix material.

Embodiment 77 is the foam composition of embodiment 76, wherein theuncrosslinked thermoplastic matrix material is selected from apolyorganosiloxane, a styrenic block copolymer, a polystyrene, apolyolefin, a polyolefin copolymer, polyvinyl chloride (PVC), ethylenevinyl acetate, polyacrylate, polymethacrylate, an acrylate copolymer,and an acrylic block copolymer. Embodiment 78 is the foam composition ofembodiment 76, wherein the uncrosslinked thermoplastic matrix materialincludes a polylactic acid (PLA). The foam composition further includesa polymer having a T_(g) of 25 degrees Celsius or greater; acrosslinking agent; and a crosslink catalyst.

Embodiment 79 is a polishing pad. The polishing pad includes a foamcomposition of any embodiments 38 to 53 or 76 to 78.

Embodiment 80 is the polishing pad of embodiment 79, wherein the foamcomposition further includes at least one channel, wherein the channelhas a depth greater than the distance the foam features extend from orinto the first major surface.

Embodiment 81 is the polishing pad of embodiment 79 or 80, furtherincluding a subpad, wherein the subpad is adjacent to the second majorsurface of the foam composition.

Embodiment 82 is the polishing pad of any of embodiments 79 to 81,having foam features extending at least one of from or into the firstmajor surface (in some embodiments, in a range from 100 micrometers to20,000 micrometers).

Embodiment 83 is the polishing pad of embodiment 82, wherein the foamcomposition includes foam features extending from the first majorsurface.

Embodiment 84 is a polishing system. The polishing system includes thepolishing pad of any of embodiments 79 to 83 and a polishing solution.

Embodiment 85 is the polishing system of embodiment 84, wherein thepolishing solution is a slurry.

Embodiment 86 is a method of polishing a substrate. The method includesproviding a polishing pad of any of embodiments 79 to 83 having aworking surface; providing a substrate having a first surface;contacting the working surface of the polishing pad with the firstsubstrate surface; and moving the polishing pad and the substraterelative to one another while maintaining contact between the workingsurface of the polishing pad and the first substrate surface. Polishingis conducted in the presence of a polishing solution.

Embodiment 87 is the method of polishing a substrate of embodiment 86,wherein the substrate is a semiconductor wafer.

The following Examples are set forth to describe additional features andembodiments of the invention. All parts are by weight unless otherwiseindicated.

Examples

Objects and advantages of this invention are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention. These examplesare merely for illustrative purposes only and are not meant to belimiting on the scope of the appended claims. Unless otherwise noted orreadily apparent from the context, all parts, percentages, ratios, etc.in the Examples and the rest of the specification are by weight.

Materials Used in the Examples

Abbreviation Description and Source Azo 1,1′-azodicarboxamide, achemical blowing agent from Sigma Aldrich (St. Louis, MO). Azo-10/901,1′-azodicarboxamide encapsulated in hydroxypropyl starch (LRS780),prepared as described in Preparative Example 5 (PE-5). Relativecomposition was 10% azodicarboxamide core and 90% hydroxypropyl starchshell. Azo-30/70 1,1′-azodicarboxamide encapsulated in hydroxypropylstarch (LRS780), prepared as described in Preparative Example 2 (PE-2).Relative composition was 30% azodicarboxamide core and 70% hydroxypropylstarch shell. Azo-50/50 1,1′-azodicarboxamide encapsulated in PVP,prepared as described in Preparative Example 3 (PE-3). Relativecomposition was 50% azodicarboxamide core and 50% PVP shell. 5PT5-phenyltetrazole, a chemical blowing agent from TCI America (Portland,OR). 5PT-5/95 5-phenyltetrazole encapsulated in hydroxypropyl starch(LRS780), prepared as described in Preparative Example 4 (PE-4).Relative composition was 5% 5-phenyltetrazole core and 95% hydroxypropylstarch shell. PTSC p-toluene semicarbazide, a chemical blowing agentfrom Alfa Aesar (Ward Hill, MA). LRS780 LYCOAT RS780, hydroxypropylstarch, a shell material from Roquette Fréres (Keokuk, IA). PVPPolyvinyl pyrrolidone k30, a shell material from TCI America (Portland,OR) with an average molecular weight of 40,000 E58144 A polyether-typethermoplastic polyurethane reported to have a glass transitiontemperature of −40° C. and a Vicat softening point of 102° C., obtainedunder the trade designation ESTANE 58144 from the Lubrizol Corporation(Brecksville, OH). E58277 A polyester-based thermoplastic polyurethanereported to have a melting transition temperature of 130° C., obtainedunder the trade designation ESTANE 58277 from the Lubrizol Corporation.I101 An engineering polyurethane thermoplastic resin reported to have aVicat temperature of 89° C., obtained under the trade designationISOPLAST 101 EPT from the Lubrizol Corporation. P85A An aromaticpolyether-based thermoplastic polyurethane reported to haveh a glasstransition temperature of −50° C. and a melting transition temperatureof 135° C., obtained under the trade designation PELLETHANE 5862-85Afrom the Lubrizol Corporation. EVA An ethylene vinyl acetate copolymer,28% vinyl acetate by weight reported to have a melting transitiontemperature of 75° C. and a Vicat temperature of 46° C., obtained underthe trade designation ELVAX 260 from DuPont Company (Wilmington, DE).D1340 A styrene-isoprene-styrene (SIS) 5 to 8 arm star block copolymerobtained from Kraton (Houston, TX). D1119 A clear, linear triblockcopolymer SIS with a styrene content of 22% obtained from Kraton. I4032DPLA Semicrystalline polylactic acid (PLA) (2 wt. % D-lactide; weightaverage molecular weight ≈200,000 g/mol); obtained under the tradedesignation INGEO 4032D obtained from Natureworks, LLC (Minnetonka, MN).I4060 PLA Amorphous polylactic acid (PLA) obtained under the tradedesignation INGEO 4060 obtained from Natureworks, LLC. VK70 PVAcPolyvinyl acetate (PVAc) (T_(g) = 42° C.; weight average molecularweight ≈400,000 g/mol); obtained under the trade designation VINAVIL K70from Vinavil (Milan, Italy). CA4 Acetyl tributyl citrate, a plasticizerobtained under the Plasticizer trade designation CITROFLEX A4 obtainedfrom Vertellus Performance Materials (Bayonne, NJ). ECO Nuc. Zincphenylphosphonate, a crystallization nucleation Agent agent obtainedunder the trade designation ECOPROMOTE obtained from Nissan ChemicalIndustrials, Ltd (Tokyo, Japan). S511 Slip/antiblock additive in PLAmasterbatch obtained under the trade designation SUKANO S511 obtainedfrom Sukano (Schindellegi, Switzerland). DSSI Dimethyl sodium sulfonateisophthalate, obtained from TCI America. HMD Hexamethylene diamine,obtained from Alfa Aesar (Tewksbury, MA) Piperazine Piperazine, obtainedfrom Alfa Aesar (Tewksbury, MA) ED Ethylene diamine, obtained from AlfaAesar (Tewksbury, MA) SA Sebacic acid, obtained from Alfa Aesar(Tewksbury, MA) TMDP 4,4′-Trimethylenedipiperidine, obtained fromSigma-Aldrich, St. Louis, MO J4370 An epoxidized styrene-acrylatecopolymer, 6,800 g/mol, glass transition temperature of 54° C., epoxyequivalence weight of 285, a crosslinking agent obtained under the tradedesignation JONCRYL 4370-F from BASF (Ludwigshafen, Germany). J4368 Anepoxidized styrene-acrylate copolymer, 6,800 g/mol, glass transitiontemperature of 54° C., epoxy equivalence weight of 285, a crosslinkingagent obtained under the trade designation JONCRYL 4368-C from BASF. DCPDicumyl peroxide, a crosslinking agent obtained from Sigma Aldrich.DTMAB Dodecyl trimethylammonium bromide, a crosslinking catalyst fromTCI America. TOAB Tetraoctylammonium bromide, a crosslinking catalystfrom Alfa Aesar. TBAI Tetrabutylammonium iodide, a crosslinking catalystfrom Eastman Kodak (Rochester, NY). P1013 PRIPOL 1013, a dimer fattyacid blend from Croda, Inc (Edison, NJ). J-ED2003 A polyetherdiaminederived from a propylene oxide capped poly(ethylene glycol) with anapproximate molecular weight of 2000 obtained under the tradedesignation JEFFAMINE ED-2003 from Huntsman Corp (The Woodlands, TX).J-ED600 A polyetherdiamine derived from a propylene oxide cappedpoly(ethylene glycol) with an approximate molecular weight of 600obtained under the trade designation JEFFAMINE ED-600 from HuntsmanCorp. ZN Zinc nitrate hexahydrate, a chemical blowing agent activatorfrom J.T. Baker (Center Valley, PA). ZS Zinc sulfate heptahydrate, achemical blowing agent activator from EMD Millipore (Burlington, MA). ZCZinc chloride, anhydrous, a chemical blowing agent activator from AlfaAesar. PN Lead nitrate, a chemical blowing agent activator from SigmaAldrich. SO Tin oxalate, a chemical blowing agent activator from SigmaAldrich. CN Cadmium nitrate tetrahydrate, a chemical blowing agentactivator from Sigma Aldrich. CA Cadmium acetate, a chemical blowingagent activator from Fisher Scientific (Waltham, MA).

Test Methods Scanning Electron Microscropy (SEM)

The cell structure of the foams was imaged by SEM using a JEOLJSM-6010LA SEM (JEOL Ltd., Tokyo, JP). Samples were prepared by using a#10 scalpel to cut thin strips of the foamed article. If the sample wasprepared by extrusion, a slice was taken in both the machine direction(MD) and transverse direction (TD) of the foamed sheet. The slice wasmounted on a JEOL SEM stage and sputter coated with Au/Pd for 30 secondsin a Denton Vacuum Desk V coating system (Denton Vacuum, LLC,Moorestown, N.J.). The images were analyzed using Image-Pro Premier 9.1or Image-Pro Premier 9.3 image analysis software (Media Cybernetics,Inc., Rockfille, Md.) to obtain cell diameter, cell density (cells/mm²),cell aspect ratio, and thicknesses of layers. Image-Pro Premier definesthe cell aspect ratio as the ratio of the major and minor axis of anellipse equivalent to the cell. Cells were defined by hand using thepolygon tool. Foam and/or skin thickness were reported based on imageanalysis of the TD, unless otherwise noted.

Light Microscopy (LM)

Foams were imaged using a Keyence VHX-2000 light microscope (KeyenceCorp., Itasca, Ill.) fitted with a Keyence VH-Z100 (100×-1000×) lens.Samples were prepared by cutting the web with a razor blade along the TDor MD of the web. The images were analyzed using Image-Pro Premier 9.1or Image-Pro Premier 9.3 image analysis software (Media Cybernetics,Inc., Rockfille, Md.) to obtain cell diameter, cell density(cells/millimeter²), cell aspect ratio, and thicknesses of layers.Image-Pro Premier defines the cell aspect ratio as the ratio of themajor and minor axis of an ellipse equivalent to the cell. Cells weredefined by hand using the polygon tool. Foam and/or skin thickness werereported based on image analysis of the TD, unless otherwise noted.

Amine and Acid Number Quantification

About 4 grams of polyamide were dissolved in 100 milliliter (mL) tolueneand 50 mL isopropyl alcohol (IPA) mixture, followed by titration with0.1N TBAOH in methanol for Acid Content or 0.15N HCl in IPA for AmineContent. The analyses were performed via a potentiometric auto-titrationsystem. All values are reported in milliequivalents per gram units.

Rheology (to Get Room Temperature Modulus for Polyamides)

A sample of polyamide weighing 0.50 g was loaded on a DHR-3 rheometerfitted with a 20-mm stainless steel parallel plate geometry as well asan EHP (electrically heated plate) temperature control accessory,available from TA Instruments (New Castle, Del.). The sample was heatedto a sufficient temperature to melt it (approximately 170-190° C.).After the sample had melted, the parallel plate geometry gap was set to1000 micrometers and the excess molten polyamide was trimmed away. Thesample was then cooled back to 25° C. over a period of approximately 60minutes with the Axial Force Control feature enabled. When the sampleattained 25° C., the rheology test was started with the followingparameters:

Geometry 20 millimeters stainless steel parallel plate geometryTemperature ramp parameters 3° C./min from 25-250° C. Strain target 0.1%Oscillatory Frequency 1 Hertz Axial force control parameters 0.0 ± 0.2Newtons in compression mode Autostrain control parameters 5.0-40000.0micronewton-meter and 0.001-10% strain

The storage modulus (G′) numbers reported in the Materials table werethe values measured at 25.0±0.2° C. under the temperature rampconditions reported in the table above.

Thermogravimetry Analysis (TGA)

Quantification of the core-shell ratio of encapsulated chemical blowingagents was performed on a TGA Q500 (TA Instruments, New Castle, Del.).The temperature was ramped at 10° C./minute from room temperature to600° C.

Spray Drying to Produce Encapsulated Chemical Blowing Agents

A slurry of polymer and chemical blowing agent was dried with acustomized Model 48 mixed flow spray dryer fabricated by Spray DryingSystems, Inc. (headquartered in Eldersburg, Md.). The spray dryer is 4foot (ft) (1.2 meter) in diameter and has 8 ft (2.4 meter) straightsides. Room air (approximately 21° C. and 50% humidity) was provided asthe bulk drying gas, which was then heated via an electric heater andcarried through the drying chamber (entered through the top and exitedthrough the bottom) and finally to a cyclone and a baghouse before beingexhausted. The cyclone separated the product solids from the gas stream(down to 1 micron in diameter); the solids were discarded. The dryinggas flow rate was unknown and changed with temperature and inlethumidity, though it was provided with a 1 HP AirTech Inc. (Rutherford,N.J.) blower (3450 RPM, 60 Hz, 230/460 V, 2.8/1.4 A). The bulk dryinggas temperature at the chamber inlet was 72-86° C., while the outlettemperature was 66-50° C. The slurry was provided at 17 (±3) grams perminute (g/min) via a dual-hose 505DU peristaltic pump (Watson Marlow,Wilmington, Mass.) using a MASTERFLEX (Vernon Hills, Ill.) 96420Platinum-cured silicone tubing line. The slurry was atomized verticallyupward utilizing internally mixed two-fluid pressure spray atomizingnozzles (available from Spraying Systems Co. (Wheaton, Ill.) under thetrade designations “FLUID CAP 2850” and “AIR CAP 1891125”). Theatomizing gas was nitrogen (20 psi) (137.9 kilopascals (kPa)), providedat 3.35 (±0.1) standard cubic feet per minute (SCFM) (approximately 94.9standard liters per minute).

PREPARATORY EXAMPLES Preparative Example 1 (PE-1)

5 grams (g) of PTSC were added to a solution of 50 g LRS780 in 300 gwater to give a 15.5 wt. % solids suspension. The suspension was furthermixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at 4000RPM for 2 minutes (min) and then filtered through a 150 micrometer (μm)sieve. The polymer mixture was then spray dried using a Buchi Mini-ProbeB-190 (Buchi Corporation, New Castle, Del.) at a pump rate of 20% and aninlet temperature set at 160° C. (outlet temperature measurement of75-80° C.). A free-flowing powder was obtained (at 32.7% yield). Theresulting particles contained 7.1 wt. % PTSC as determined by TGA.

Preparative Example 2 (PE-2)

750 g of AZO powders were added to a solution of 1750 g of LRS780 in 10kilograms (kg) of water to give a 20 wt. % solid suspension. Thesuspension was further mixed with a high shear mixer (T50 digital UltraTurrax, IKA) at 2000 RPM for 5 min. This polymer mixture was then spraydried (using the Spray drying method described above) to put a polymershell around the particles. 1701 g of free-flowing powders were obtained(at 68.0% yield). The resulting composite particles contained 30 wt. %of AZO.

Preparative Example 3 (PE-3)

1500 g of AZO powders were added to a solution of 1500 g PVP in 9000 gof water to give a 25 wt. % solid suspension. The suspension was furthermixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at 2000RPM for 5 min. This polymer mixture was then spray dried (using theSpray drying method described above) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 78.0% yield). Theresulting composite particles contained 50 wt. % of AZO.

Preparative Example 4 (PE-4)

500 grams (g) of PT were suspended in a solution of 2000 g LRS780 in14.17 kilograms water to give a 15 wt. % solids suspension. Thesuspension was further mixed with a high shear mixer (T50 digital UltraTurrax, IKA) at 2000 rpm for 5 min. This polymer mixture was then spraydried (using the Spray drying method described above) to put a polymershell around the particles. 1021 g of free-flowing powders were obtained(at 40.8% yield). The resulting capsule contained 5.1 wt. % of PT.

Preparative Example 5 (PE-5)

278 grams (g) of AZO powders were added to a solution of 2.5 kilogram(kg) of LRS780 in 11.1 kg of water to give a 20 wt. % solid suspension.This polymer mixture was then spray dried to put a polymer shell aroundthe particles using a Niro Mobil Minor lab spray-dryer fabricated by GEAGroup AG (headquartered in Dusseldorf, Germany). The suspension wassprayed in portions. Each portion was mixed with a high shear mixer for1-2 minutes and passed through a 425 μm screen immediately beforeentering the spray dryer. The bulk drying gas temperature was maintainedbetween 90-92° C. at the outlet. The slurry was atomized verticallyupward utilizing internally mixed two-fluid pressure spray atomizingnozzles (available from Spraying Systems Co. (Wheaton, Ill.) under thetrade designations “FLUID CAP 60100” and “AIR CAP 120”). 1476 g offree-flowing powders were obtained (at 37% yield). The resultingcomposite particles contained 10 wt. % of AZO.

Preparative Example 6 (PE-6)

15 g of AZO powders were added to a solution of 30 g PVP and 30 g ZN in90 g of water to give a 45 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 135° C. (outlettemperature measurement of 77-84° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 40.9% yield). Theresulting capsule contained 34 wt. % AZO.

Preparative Example 7 (PE-7)

15 g of AZO powders were added to a solution of 30 g PVP and 45 g ZN in90 g of water to give a 50 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 135° C. (outlettemperature measurement of 74-85° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 38.4% yield). Theresulting capsule contained 50 wt. % AZO.

Preparative Example 8 (PE-8)

10 g of AZO powders were added to a solution of 20 g LRS780 and 20 g ZNin 80 g of water to give a 38 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 79-83° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 30.4% yield). Theresulting capsule contained 21 wt. % AZO.

Preparative Example 9 (PE-9)

10 g of AZO powders were added to a solution of 20 g LRS780 and 20 g ZSin 80 g of water to give a 38 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 78-84° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 30.4% yield). Theresulting capsule contained 27 wt. % AZO.

Preparative Example 10 (PE-10)

10 g of AZO powders were added to a solution of 20 g PVP and 20 g ZS in75 g of water to give a 40 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 139° C. (outlettemperature measurement of 83° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 4.9% yield). Theresulting capsule contained 24 wt. % AZO.

Preparative Example 11 (PE-11)

10 g of AZO powders were added to a solution of 20 g LRS780 and 20 g ZCin 80 g of water to give a 38 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 81-84° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 31.4% yield). Theresulting capsule contained 11 wt. % AZO.

Preparative Example 12 (PE-12)

10 g of AZO powders were added to a solution of 20 g LRS780 and 5 g ZCin 80 g of water to give a 30 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 81-85° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 42.3% yield). Theresulting capsule contained 21 wt. % AZO.

Preparative Example 13 (PE-13)

10 g of AZO powders were added to a solution of 20 g LRS780 and 20 g PNin 80 g of water to give a 38 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 81-84° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 31% yield). Theresulting capsule contained 17 wt. % AZO.

Preparative Example 14 (PE-14)

10 g of AZO powders were added to a solution of 20 g LRS780 and 20 g SOin 100 g of water to give a 33 wt. % solid suspension. The suspensionwas further mixed with a high shear mixer (T50 digital Ultra Turrax,IKA) at 2000 RPM for 5 min. The polymer mixture was then spray driedusing a Buchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) ata flow rate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 81-84° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 35% yield). Theresulting capsule contained 25 wt. % AZO.

Preparative Example 15 (PE-15)

10 g of AZO powders were added to a solution of 20 g LRS780 and 20 g CNin 80 g of water to give a 38 wt. % solid suspension. The suspension wasfurther mixed with a high shear mixer (T50 digital Ultra Turrax, IKA) at2000 RPM for 5 min. The polymer mixture was then spray dried using aBuchi Mini-Probe B-190 (Buchi Corporation, New Castle, Del.) at a flowrate of 15 rpm and an inlet temperature set at 130° C. (outlettemperature measurement of 81-84° C.) to put a polymer shell around theparticles. A free-flowing powder was obtained (at 33% yield). Theresulting capsule contained 17 wt. % AZO.

General Procedure for the Preparation of Polyamides

All monomers were placed in a 1 liter (L) resin flask fitted with athermocouple, overhead stirrer and a distillation head. The distillationhead was fitted with a 100 mL receiver flask. The reaction was heatedusing an electric mantle and a temperature controller. The distillationhead condenser was cooled with ambient temperature water. The reactionwas heated to 160° C. over a period of 1.5 hours and held at thattemperature until the distillation rate slowed down. The reaction wasthen heated to 225° C. and held at that temperature until thedistillation rate slowed down. A 20 mmHg vacuum was introduced in theflask over a period of 5 minutes. The reaction was held under vacuum for1 hour when the vacuum was broken with nitrogen gas. The contents werethen drained and collected. The below polyamide preparative exampleswere prepared according to the General Procedure, then analyzed by theAmine and acid number quantification and Rheology test methods.

Polyamide Preparative Examples (PA-1 to PA-7)

PA-1 A polyamide made from 64.5/11.4 parts by weight blend ofP1013/sebacic acid and a 18.7/5.4 parts by weight blend of4,4′-Trimethylenedipiperidine/ethylene diamine, and determined to havean amine number = 5.6 mg KOH/g. PA-2 A polyamide made from a 92/8 partsby weight blend of P1013/ sebacic acid and ethylene diamine, anddetermined to have an acid number = 9.9 mg KOH/g, and a storage modulusG′(25° C.) = 80.6 MPa. PA-3 A polyamide made from a 68.2/14.7 parts byweight blend of P1013/sebacic acid and a 12.9/1.8/2.3 parts per weightblend of piperazine/ethylene diamine/hexamethylene diamine, anddetermined to have an amine number = 6.1 mg KOH/g, and a storage modulusG′(25° C.) = 2.0 MPa. PA-4 A polyamide made from a 68.2/14.7 parts perweight blend of P1013/sebacic acid and a 12.9/0.6/4.6 parts per weightblend of piperazine/ethylene diamine/hexamethylene diamine, anddetermined to have an amine number = 7.4 mg KOH/g, and a storage modulusG′(25° C.) = 0.7 MPa. PA-5 A polyamide made from a 68.3/8.6/2.5 partsper weight blend of P1013/sebacic acid/dimethyl sodium sulfonateisophthalate and a 7.6/3.1/9.8 parts per weight blend ofpiperazine/ethylene diamine/ J-ED600, and determined to have an acidnumber = 19.6 mg KOH/g, and a storage modulus G′(25° C.) = 1.7 MPa. PA-6A polyamide made from 262/369 parts by weight blend of sebacicacid/P1013 and 201 parts by weight piperazine, and determined to have anamine number = 9.5 mg KOH/g, and a storage modulus G′(25° C.) = 480 MPa.PA-7 A polyamide made from 401/115 parts by weight P1013/sebacic acidand 51/40/133 parts by weight piperazine/ethylene diamine/ J-ED2003, anddetermined to have an amine number = 3.4 mg KOH/g, and a storage modulusG′(25° C.) = 33 MPa.

Crosslinking of Polyamide Resins

Polyamide resins were compounded in a Brabender twin-screw mixer (C.W.Brabender Instruments, Inc., South Hackensack, N.J., model ATRPlasti-Corder) at 100 revolutions per minute (RPM) at 200° C. by mixingpolyamide resins with crosslinking agents and/or crosslinking catalyststo make foam compositions, except PA-5 which was mixed at 150° C.

TABLE 1 Crosslinker Catalyst Polymer Type wt. % Type wt. % PA-1 J43702.2 — — PA-2 J4370 4.3 DTMAB 1.0 PA-3 J4368 2.5 — — PA-4 J4368 2.9 — —PA-5 J4368 8.0 TBAI 4.0 PA-6 J4368 4.0 — — PA-7 J4368 2.0 — —

Examples Preparation of Polymer Prefoam Resins

Polymer resins were compounded in a Brabender twin-screw mixer (C.W.Brabender Instruments, Inc., South Hackensack, N.J., model ATRPlasti-Corder) at 100 revolutions per minute (RPM) at the indicatedtemperatures (according to Tables 2 and 3) by mixing polymer resins withcrosslinking agents and/or chemical blowing agents and/or crosslinkingcatalysts.

Preparation of Polymer Prefoam Sheets

Compounded prefoam resins were pressed between two aluminum sheets withpolytetrafluoroethylene liners and a 1.5 mm shim in a Carver press(Carver, Inc., Wabash, Ind., model #2699). The Carver press was set atthe indicated temperatures (according to Tables 2 and 3). The resin wassoftened for 1-3 minutes (min) and then pressed at 6 metric tons for 1min.

In the tables that follow, Comparative Examples are indicated by Comp.Ex. and Examples are indicated by Ex.

TABLE 2 Com- pounding Carver Azo- temper- temper- Azo, 30/70, PA-1,PA-2, PA-3, PA-4, PA-6, PA-7, J4370, J4368, DTMAB, ature, ature, Examplewt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % ° C. °C. Comp. Ex. A 2 92.8 4.2 1.0 150 155 Comp. Ex. B 6.3 89.7 4.2 150 155Comp. Ex. C 3 94.5 2.5 125 135 Ex. 1 6.3 88.7 4 1.0 150 155 Ex. 2 1087.8 2.2 125 110 Ex. 3 6.5 91.5 2 110 135 Ex. 4 10 87.4 2.6 110 135 Ex.5 10 86.4 3.6 155 155 Ex. 6 10 88.2 1.8 166 166

TABLE 3 Com- pounding Carver 5PT- temper - temper- 5PT, 5/95, PTSC,PE-1, PA-2, E58277, J4370, DTMAB, ature, ature, Example wt. % wt. % wt.% wt. % wt. % wt. % wt. % wt. % ° C. ° C. Comp. Ex. D 2 92.8 4.2 1 150160 Comp. Ex. E 2 98 160 180 Ex. 7 10 85.9 3.9 1 150 160 Ex. 8 6 94 160180

Foaming in an Oven

A 0.7 inch (1.78 centimeters (cm)) by 0.06 inch (0.15 cm) disk ofmelt-pressed polymer prefoam sheet was placed on a Teflon liner andplaced in an oven set between 210-270° C. Samples were foamed for 0-15minutes. FIG. 2 shows SEM images of articles (Comp. Ex. A to Comp. Ex.E, Ex. 1, Ex. 2, Ex. 7, Ex. 8) that were foamed in an oven at differenttemperatures.

TABLE 4 Oven foaming temperatures. Sample Foaming Temperature Comp. Ex.A 230° C. Comp. Ex. B 230° C. Ex. 1 230° C. Comp. Ex. C 230° C. Ex. 2230° C. Ex. 3 230° C. Ex. 4 230° C. Ex. 5 230° C. Ex. 6 230° C. Comp.Ex. D 270° C. Ex. 7 270° C. Comp. Ex. E 270° C. Ex. 8 270° C.

TABLE 5 Analysis of the final foam compositions Foaming Average Celldensity, Cell time, cell size, cells/square aspect Example minutesmicrometers millimeter ratio Ex. 1 5 163 ± 126 21.5 1.4 Comp. Ex. A 5Cells Merged Comp. Ex. B 5 Cells Merged Ex. 2 3.9 151 ± 122 26.5 1.4Comp. Ex. C 4 Cells merged Ex. 3 6 159 ± 156 26.9 1.4 Ex. 4 3.5 198 ±80  21.2 1.3 Ex. 5 4 127 ± 57  48.6 1.5 Ex. 6 5 146 ± 76  27.3 1.5 Ex. 76.5 160 ± 221 7.1 1.4 Comp. Ex. D 6.5 624 ± 345 1.6 1.2 Ex. 8 6.5 170 ±91  14.6 1.3 Comp. Ex. E 5 323 ± 123 8.9 1.4

Foaming in an Extruder, General Information

Single layer films were produced using the twin screw extruder connectedto a single layer die. Three-layer films were produced by using threeextruders connected to a three-layer die. The equipment used is listedin Table 6 below.

TABLE 6 EQUIPMENT DESCRIPTION AND SOURCE 25 mm twin screw Twin screwextruder, type ZSK-25 manufactured by Krupp Werner & extruder (TSE)Pfleiderer, Ramsey, NJ, USA. Two 1.25” (32 1.25” (32 mm) single screwextruder manufactured by Killion Extruders mm) single screw Inc., CedarGrove NJ, USA extruders (SSE) Two K-Tron Loss-in-weight solids feeders,model KCL-KT20, manufactured by feeders K-Tron America, Pitman, NJ, USACasting station 3-roll stack casting station, model KXE-512,manufactured by Davis Standard, Pawcatuck, CT, USA Multi-layer 3-layerfilm extrusion die, 6” (15 cm) wide, manufactured by Premiere extrusiondie Dies Corp., Chippewa Falls, WI Single layer Single layer filmextrusion die, 6” (15 cm) wide, conventional extrusion die coat-hangerdesign with flexible lip. Heated hoses Heated hoses manufactured byDiebolt & Co., Springfield, MA, USA.

Foaming in an Extruder, Single Layer

Single layer foams were made using a TSE connected to a single layerdie. Both K-tron feeders fed solids (powder and pellets) into the TSE.To ensure good mixing of the filler into the polymer the TSE screw speedwas set to 125 revolutions per minute (RPM). The TSE was connected tothe single layer die via a heated hose. The cast film was extruded outof the single layer die onto a cooling roll in the casting station.Cooling of the casting roll was achieved by plumbing city water throughthe chrome plated casting roll. The film was then wound into a roll. Ifblends of polymers were used, the pellets were mixed by hand and fedusing the same K-tron feeder into the extruder. The TSE conditions usedare listed in Table 7 below. The polymer and blowing agents used forsingle layer foams are shown in Table 8.

TABLE 7 Polymer feed rate 10 lb/hr (pounds/hour) eCBA feed rate 0.1-0.9pounds per hour (lbs/hr) Barrel temperature 350° F. (all zones, 10 zonestotal) Polymer added Zone 1 Blowing agent added Zone 8 Neck tubetemperature 360° F. Roller temp 55° F.

TABLE 8 Azo, Azo-10/90, Azo-30/70, Azo-50/50, E55144, E55277, P85A,PA-1, J4370, Example wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt.% Comp. Ex. F 0.8 49.6 49.6 Ex. 9 1 49.5 49.5 Ex. 10 3 48.8 48.8 Ex. 115 47.5 47.5 Ex. 12 7.5 46.25 46.25 Ex. 13 9 45.5 45.5 Ex. 14 3 97 Ex. 151 99 Ex. 16 3.6 96 0.4 Ex. 17 1.4 98.1 0.5

TABLE 9 SEM analysis of Ex. 9 to Ex. 17 Die tem- Average Cell density,Cell Sheet Orien- perature, cell size, cells/square aspect thickness,Example tation ° C. micrometer millimeter ratio millimeter Ex. 9 TD 39044 ± 20 28.6 1.7 0.22 MD 49 ± 20 4.5 2.7 Ex. 10 TD 475 56 ± 41 84.6 1.50.91 MD 475 56 ± 39 89.8 1.4 Ex. 11 TD 430 30 ± 17 476 1.4 0.55 MD 32 ±17 469 1.4 Ex. 12 TD 430 56 ± 35 106 1.3 1.03 MD 52 ± 30 139.2 1.4 Ex.13 TD 430 52 ± 33 137 1.3 0.91 MD 66 ± 38 98.2 1.6 Ex. 14 TD 410 65 ± 4651.8 1.6 0.90 MD 410 64 ± 45 48.9 2.2 Ex. 15 TD 400 45 ± 36 153.2 1.50.83 MD 400 54 ± 36 138.5 1.6 Ex. 16 TD 400 65 ± 34 58.9 2.2 0.74 MD 40064 ± 31 51.0 2.8 Ex. 17 TD 400 84 ± 49 24.2 1.4 2.49 MD 400 104 ± 97 20.4 1.5

Foaming in an Extruder, Multilayer

To make 3-layer film, two SSEs gravity fed polymer pellets into theouter skin layers of the multilayer construction. Both K-tron feedersfed solids (powder and pellets) into the 25 mm twin screw extruder.Polymer solids were added in Zone 1, blowing agent solids were added inZone 6. To ensure good mixing of the filler into the polymer the TSEscrew speed was set to 125 RPM. All extruders were connected to the3-layer die via heated hoses. The twin screw extruder fed the core(center) layer of the 3-layer die. The 3-layers of polymer melt werejoined inside the multi-layer die and the 3-layer molten film was castonto a cooling roll in the casting station. The resulting 3-layer filmwas wound into a roll. Cooling of the casting roll was achieved byplumbing city water through a chrome finished steel roll. The feed rateof the skin layers was either 5 lbs/hr or 2.5 lbs/hr for each skinlayer. The line speed was 5 feet per minute. All TPU pellets used forthe 3-layer films were P85A. The TSE conditions used are listed in Table10 below. The polymer and blowing agents used for multilayer foams areshown in Tables 11, 12, 13, and 14.

TABLE 10 TSE conditions Barrel temperature 360° F. (182° C.) (all zones,10 zones total) Neck tube temperature 360° F. (182° C.) Die temp 400° F.(204° C.) Roller temp 55° F. (13° C.)

TABLE 11 Example 18 (Ex. 18) Extruder Layer Composition Extrusion RateSSE Top/bottom P85A 5 lbs/hr (2.27 kilogram per hour (kg/hr)) TSE Core99.5% P85A, 10 lbs/hr (4.54 kg/hr) 0.5% Azo-30/70

TABLE 12 Example 19 (Ex. 19) Extruder Layer Composition Extrusion RateSSE Top/bottom P85A 5 lbs/hr (2.27 kg/hr) TSE Core 99% P85A, 10 lbs/hr(4.54 kg/hr) 1% Azo-30/70

TABLE 13 Example 20 (Ex. 20) Extruder Layer Composition Extrusion RateSSE Top/bottom P85A 2.5 lbs/hr (2.27 kg/hr) TSE Core 99% P85A, 10 lbs/hr(4.54 kg/hr) 1% Azo-30/70

TABLE 14 Example 21 (Ex. 21) Extruder Layer Composition Extrusion RateSSE Top/bottom P85A 2.5 lbs/hr (2.27 kg/hr) TSE Core 99% P85A, 10 lbs/hr(4.54 kg/hr) 5% Azo-10/90

TABLE 15 SEM analysis of Ex. 18 to Ex. 21 Cell Total Skin Averagedensity, Cell sheet thickness Ex- Orien- cell size, cells/square aspectthickness, of 1 layer, ample tation micrometer millimeter ratiomillimeter micrometer Ex. 18 TD 178 ± 64 9.1 1.8 0.74 131 MD 232 ± 745.6 2.5 0.73 146 Ex. 19 TD 121 ± 56 30.2 1.6 0.95 149 MD 172 ± 60 21.02.4 0.96 150 Ex. 20 TD 119 ± 63 27.6 1.6 0.75 122 MD 138 ± 66 23.3 2.30.75 119 Ex. 21 TD 124 ± 49 21.9 1.8 0.86 150 MD 144 ± 66 16.0 2.7 0.83162Foaming in an Extruder with a Patterned Tool

FIG. 1 shows an exemplary apparatus for the method of making a patternedpolymeric foam layer described herein. Referring to FIG. 1, apparatus 99has rotating tool roll 110 with major circumferential surface 111 andextrusion die 112 with die lip 113 spaced in proximity of tool roll 110to form gap 115 between tool roll 110 and extrusion die 112. Polymer 117comprising a foaming agent is injected onto portion 120 of majorcircumferential surface 111 tool roll 110. Portion 120 of majorcircumferential surface 111 is in proximity of die lip 113. Polymer 117foams to provide polymeric foam layer described herein 100.

To make a patterned foam sheet, an apparatus as generally shown in FIG.1 was used. The extrusion die was 20.3 cm (8 inches) wide (obtainedunder the trade designation “MASTERFLEX” (Model LD-40) from Cloeren,Orange, Tex.) configured with the die positioned on the top of the toolroll at top dead center. The die was orientated such that the bottom ofthe die was on the trailing edge of the tooling roll. The bottom die liphad a 3.18 mm (0.125 inch) land. The extruder was a 40 mm (1.57 inches)twin screw extruder (obtained from (Model ZE 40x40D) Berstorff,Charlotte, N.C.). The twin screw extruder used screw elements to helpdisperse and mix the polymer. The extrusion temperature set points usedare shown in Tables 16 and 17 (below) for resins E51844/E58277 and 1101,respectively.

TABLE 16 Resin E51844/E58277 Extruder type Twin-screw Screw rpm 100 TPUfeed rate 10 lb/hr Zone 1 135° C. Zone 2-Zone 4 175° C. Zone 5-Zone 6190° C. Zone 7-Zone 10 200° C. Blowing agent added Zone 1 Neck tubetemperature 200° C. tool temp 100° F. Gap between die lip and tool 762micrometers

TABLE 17 Resin I101 Extruder type Twin-screw Screw rpm 100 TPU feed rate10 lb/hr Zone 1 135° C. Zone 2 175° C. Zone 3 180° C. Zone 4 190° C.Zone 5-Zone 6 210° C. Zone 7-Zone 9 220° C. Zone 10 200° C. Blowingagent added Zone 1 Neck tube temperature 220° C. tool temp 180° F. Gapbetween die lip and tool 508 micrometers

A single tooling roll station was used with the die mounted at the topdead center of the roll. The die was mounted on linear slides to move inthe up and down direction. The roll was nominally 30.5 cm (12 inch) indiameter with a 40.6 cm (16 inch) face width. The tooling roll hadinternal water cooling with spiral wound internal channels. A 37.5 cm(14.75 inch) outside diameter aluminum tooling shell was mounted ontothe outer surface roll.

The linear motion of the die was controlled by linear actuators to movethe die and to control the gap between the die lip and tooling roll.

The tooling roll shell had rectangular indentations machined into thesurface of the aluminum shell. The rectangular indentations were 3.69 mm(0.145 inch) wide by 5.90 mm (0.232 inch) apart. The corners of theindentations had a 0.75 mm (0.030 inch) radius. The tooling roll was setwith a cooling temperature set point of 37.8° C. (100° F.). The linespeed was 0.24 meters (0.8 feet) per minute.

The polymers were feed using Ktron loss-in-weight solids feeders, modelLIWT20 by K-Tron America, Pitman, N.J., USA, into the 40 mm twin screwextruder. If a blend of polymers were used, pellets were dry mixed andthen feed using the same Ktron feeder.

Compositions used to make patterned foam sheets are shown in Table 18below.

TABLE 18 Azo- Azo- 5PT- Azo, 10/90, 30/70, 5/95, E55144, E55277, I101,Example wt. % wt. % wt. % wt. % wt. % wt. % wt. % Comp. Ex. G 0.5 49.7549.75 Ex. 22 2.3 48.85 48.85 Ex. 23 1.5 49.25 49.25 Ex. 24 2.5 97.5

TABLE 19 SEM analysis of Comp. Ex. G, Ex. 22, and Ex. 23 Smooth Die Tem-Average Cell density, Cell backside, perature, Orien- cell size,cells/square aspect Example Yes/No ° C. tation micrometer millimeterratio Comp. No 218 TD 35 ± 22 197.5 1.81 Ex. G MD 81 ± 77 37.7 3.89Comp. Yes 246 TD 108 ± 89  15.2 2.10 Ex. G MD 67 ± 52 15.8 4.36 Ex. 22No 218 TD 47 ± 27 119.5 1.61 MD 46 ± 27 115.2 2.11 Ex. 23 Yes 229 TD 37± 18 76.3 1.52 MD 48 ± 29 72.0 1.94 Ex. 23 Yes 246 TD 36 ± 19 189.7 1.60MD 41 ± 19 130.6 1.93

FIGS. 5A-5D show SEM images of Comp. Ex. G and Ex. 23 extruded into apatterned tool, each at a die temperature of 246° C. Cross-sections weretaken of protruding post structures. A comparison of FIG. 5A (i.e.,Comp. Ex. G sliced in the transverse direction), and FIG. 5B (i.e.,Comp. Ex. G sliced in the machine direction), illustrates a significantdifference in the cell aspect ratio in the transverse direction versusthe machine direction. In contrast, a comparison of FIG. 5C (i.e., Ex.23 sliced in the transverse direction), and FIG. 5D (i.e., Ex. 23 slicedin the machine direction) illustrates a smaller difference in cellaspect ratio in the transverse direction versus the machine direction.

TABLE 20 LM analysis of Ex. 24 Cell density, Die Average cellcells/square Cell aspect Example Temperature, ° C. Orientation size,micrometer millimeter ratio Ex. 24 285 TD 86 ± 44 37.8 2.01 Ex. 24 302TD 25 ± 11 115.2 1.71

FIG. 7A-7B show LM images of Ex. 24. The foam composition imaged in FIG.7A was made using a die temperature of 285° C.; the foam compositionimaged in FIG. 7B was made using a die temperature of 302° C.

Thermogravimetric Analysis (Tga) of Co-Encapsulated Composite Particles

The decomposition profiles of the composite particles were determinedusing a TGA Q500 (TA Instruments, New Castle, Del.) using a temperatureramp rate of 10° C./min from 40 to 110° C., isothermal for 10 min, ramprate of 10° C./min from 110 to 90° C., isothermal for 2 min, ramp rateof 10° C./min from 90 to 600° C. The run was tared by placing a standardaluminum differential scanning calorimetry (DSC) pan in a platinum TGApan. Then, 5-10 mg of each sample was added to a tared pan for analysis.The T_(start) (i.e., onset temperature of thermal decomposition) andT_(max) (i.e., temperature at which thermal decomposition occurs at amaximum rate) were determined using TA Instruments Universal Analysissoftware. T_(start) is defined as the first temperature above 100° C.during the final temperature ramp where the Derivative Weight (%/° C.)was 0.02%/° C. T_(max) is defined as the first local maximum temperatureabove T_(start).

TABLE 21 The effect of co-encapsulating blowing agent accelerators.Co-encapsulating AZO with ZN (PE-6, PE-7, PE-8), ZS (PE-9, PE-10), ZC(PE-11, PE-12), ZA (PE-13), PN (PE-14), SO (PE-15), CN (PE-16), or CA(PE-17), lowered the T_(start) and T_(max) of the particle as comparedto encapsulating AZO alone (PE-2). Sample T_(start), ° C. T_(max), ° C.PE-2 187 224 PE-6 139 201 PE-7 126 178 PE-8 151 172 PE-9 168 211 PE-10163 206 PE-11 127 153 PE-12 178 194 PE-13 164 195 PE-14 170 211 PE-15127 174

Preparative Example PLA (PE-PLA)

A twin screw extruder from APV Chemical Machinery (Saginaw, Mich.)(screw diameter: 30 mm; ratio of screw length to diameter: 30; extrusionthroughput rate: 20 pounds per hour (9 kilograms/hour); Zone 1: 250° F.(121° C.); Zones 2 and 3: 390° F. (199° C.); Zones 4 and 5: 350° F.(177° C.)) and an underwater pelletizer from Gala Industries (EagleRock, Va.) were used to prepare pre-compounded and free-flowing PLApellets (formulation listed in Table 2). The PE-1 pre-compounded PLApellets were used as the base resin to prepare foam samples.

TABLE 22 Formulation of PE-PLA Components Composition, wt. % I4060 PLA30 I4032D PLA 7.8 VK70 PVAc 35 CA4 Plasticizer 25 ECO Nuc. Agent 0.2S511 2

TABLE 23 Com- pounding Carver PE- temper- temper- Azo, PE-6, PE-8,PE-11, ZN, PLA, EVA, D1340, D1119, PA-5, J4368, TOAB, TBAI, DCP, atureature Example wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt.% wt. % wt. % wt. % wt. % ° C. ° C. Comp. 1.6 4.8 93.2 0.6 0.2 100 100Ex. H Comp. 1.5 4.4 82.9 7.5 3.7 90 110 Ex. J Ex. 25 10 89.2 0.6 0.2 100100 Ex. 26 10 89.2 0.6 0.2 100 100 Ex. 27 10 90 90 90 Ex. 28 10 88.5 1.590 90 Ex. 29 10 90 90 90 Ex. 30 10 9 81 110 110 Ex. 31 9.9 79.9 7.1 3.190 110

TABLE 24 Foaming Average Cell density, Cell time, Foaming cell size,cells/square aspect Example minutes temp, ° C. micrometers millimeterratio Ex. 25 8 150 134 ± 72 32.4 1.3 Comp. 8 150  207 ± 257 5.3 1.4 Ex.H Ex. 26 12 160 190 ± 97 20.6 1.7 Ex. 27 6.5 150 256 ± 99 13.7 1.4 Ex.28 6.5 150 233 ± 77 15 1.4 Ex. 29 9 150  323 ± 129 7.9 1.3 Ex. 30 5 190192 ± 56 10.4 1.2 Ex. 31 12 150 152 ± 90 33.0 1.2 Comp. 12 150  240 ±208 8.1 1.2 Ex. I

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. To the extent thatthere is any conflict or discrepancy between this specification aswritten and the disclosure in any document that is incorporated byreference herein, this specification as written will control. Variousmodifications and alterations to this disclosure will become apparent tothose skilled in the art without departing from the scope and spirit ofthis disclosure. It should be understood that this disclosure is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the disclosureintended to be limited only by the claims set forth herein as follows.

1. A composition comprising: an uncrosslinked thermoplasticnitrogen-containing matrix material and a plurality of compositeparticles distributed in the uncrosslinked thermoplasticnitrogen-containing matrix material, wherein the composition exhibits anelastic modulus of 0.5 megaPascals (MPa) or greater, and wherein theplurality of composite particles each comprises: a chemical blowingagent particle encapsulated within a shell comprising an uncrosslinkedthermoplastic material, wherein the uncrosslinked thermoplastic materialexhibits a complex viscosity of 3,700 Pa·s or greater at a decompositiontemperature of the chemical blowing agent particle.
 2. The compositionof claim 1, wherein the uncrosslinked thermoplastic nitrogen-containingmatrix material comprises a polyurethane.
 3. The composition of claim 1,wherein the uncrosslinked thermoplastic nitrogen-containing matrixmaterial comprises an acid-terminated polyamide or an amine-terminatedpolyamide.
 4. The composition of claim 1, further comprising acrosslinking agent, a crosslink catalyst, or both.
 5. The composition ofclaim 1, wherein the plurality of composite particles is present in anamount of 0.1 to 20 wt. %, 0.5 to 15 wt. %, 0.5 wt. % to 10 wt. %, 1 to8 wt. %, or 10 to 17 wt. %, inclusive, of the total composition.
 6. Thecomposition of claim 1, wherein the chemical blowing agent is selectedfrom a diazocompound, a sulfonyl hydrazide, a tetrazole, anitrosocompound, an acyl sulfonyl hydrazide, hydrazones, thiatriazoles,azides, sulfonyl azides, oxalates, thiatrizene dioxides, isatoicanhydride, or combinations thereof.
 7. The composition of claim 1,wherein the chemical blowing agent is 1,1-azodicarboxamide,5-phenyltetrazole, or p-toluenesulfonylhydrazine.
 8. (canceled)
 9. Afoam composition comprising: a closed cell foam thermoplasticnitrogen-containing matrix material and an uncrosslinked thermoplasticmaterial distributed in the closed cell foam thermoplasticnitrogen-containing matrix material, wherein the uncrosslinkedthermoplastic material is present as a plurality of particulates. 10.(canceled)
 11. The foam composition of claim 9, wherein the foamcomposition comprises a smooth major surface and an opposing majorsurface comprising replicated features.
 12. The foam composition ofclaim 9, having an average cell size of 250 micrometers or less, 150micrometers or less, 120 micrometers or less, 100 micrometers or less,80 micrometers or less, or 60 micrometers or less.
 13. The foamcomposition of claim 9, wherein the thermoplastic nitrogen-containingmatrix material comprises a polyamide, a polyurethane, or apolyetherimine, a polyethyleneimine, a polyimide, a polyurea, apolyoxazoline, a polyiminothioether, a polyaminoamide, apolysulfonamide, or polyetherimide, poly(amide imide), poly(esteramide), or combinations thereof.
 14. The foam composition of claim 9,wherein the foam composition has a cell density of 1 to 1,000 cells persquare millimeter (cells/mm²) or 4 to 500 cells/mm².
 15. (canceled) 16.An article comprising the foam composition of claim 9 attached to asubstrate.
 17. The article of claim 16, wherein the article is amultilayer article and the foam composition is a layer of foam disposedin between a layer of a second material and a layer of a third material.18. A method of making a foam composition of claim 9, the methodcomprising: a) compressing a mixture comprising: an uncrosslinkedthermoplastic nitrogen-containing matrix material and a plurality ofcomposite particles distributed in the uncrosslinked thermoplasticnitrogen-containing matrix material, wherein the mixture exhibits anelastic modulus of 0.5 megaPascals (MPa) or greater, and wherein theplurality of composite particles each comprises: a chemical blowingagent particle encapsulated within a shell comprising an uncrosslinkedthermoplastic material, wherein the uncrosslinked thermoplastic materialexhibits a complex viscosity of 3,700 Pa·s or greater at a decompositiontemperature of the chemical blowing agent particle; and b) heating thecompressed mixture, thereby forming the foam composition.
 19. The methodof claim 18, wherein the mixture is compressed, heated, or both in amultilayer extruder.
 20. (canceled)
 21. The method of claim 18, furthercomprising casting the mixture into a replication mold while the heatedmixture is forming the foam composition, thereby imparting a pluralityof replicated features on a major surface of the foam composition.
 22. Acomposite particle comprising: a chemical blowing agent particleencapsulated within a shell comprising an uncrosslinked thermoplasticmaterial; and a co-encapsulated metal salt of the form MX or M(X)₂,wherein M is zinc, calcium, cadmium, potassium, barium, strontium,magnesium, mercury, titanium, tin, lead, sodium, lithium, or cesium,wherein X is an organic ligand or an inorganic ligand containing anitrate, phosphate, phosphite, sulfate, carbonate, oxalic acid, halide,para-toluenesulfonate, tetrafluoroborate, perchlorate, hydroxide, orcyanide moiety, or the corresponding hydrates, and wherein theuncrosslinked thermoplastic material exhibits a complex viscosity of3,700 Pascal seconds (Pa·s) or greater at a decomposition temperature ofthe chemical blowing agent particle.
 23. A polishing pad comprising afoam composition of claim
 9. 24. A polishing system comprising thepolishing pad of claim 23 and a polishing solution.